None of the information below has been officialy announced by Blizzard, this is only a compilation of information gathered from reliable sources. Just keep in mind that it takes a LOT to make me post something on the front page and I'm definitely not speculating here.
Other sites started it, I'll try to finish it. Think twice before you read this post, we have a lot of spoilers here.
Most of this stuff will be announced at the Blizzcon anyway, if you didn't take the time to order the live stream you might want to consider doing it. We will probably see a lot of interesting things here.
Quote from: Blizzard (Source)
This year, for the first time, you'll have the opportunity to enjoy a live Internet stream of BlizzCon coverage from the comfort of your own home. The stream includes the same content as the DIRECTV pay-per-view event, but you do not have to be a DIRECTV subscriber to purchase it. It consists of over 16 hours of video, including interviews and commentary, main stage presentations, and tournament coverage. It’s now available to order for $39.95, and purchasers will also receive the BlizzCon 2009-exclusive in-game pet, Grunty the Murloc Marine (not available in all regions). Head over to the BlizzCon 2009 Live Stream website to get more information, to test video playback on your system, or to place an order.
http://blizzcon.rayv.com/Forums - The WoW Cataclysm General Discussions forum is now available.
Update - Another update from the Something Awful forums has been confirmed and is now integrated to the post. (The original quote was removed by the author's request on SA)
World of Warcraft: Cataclysm
World of Warcraft: Cataclysm is the next expansion for World of Warcraft. Dark and forgotten threats that have long stayed out of sight have finally arrived on our shores, unleashing a cataclysmic event upon Azeroth and now preparing more nefarius plans to take it back.
Level Cap
The level cap in the next expansion will be slightly lower than expected this time around; 85.
This suggests Blizzard wants more room for expansions before hitting the level 100 cap. With less leveling to do (along with the revamped leveling listed below likely to increase the speed and ease of leveling), leveling a new race remains appealing for new and existing players alike.
Leveling from 80-85 should be a much bigger deal, the idea is to make sure that gaining a level really means something and doesn't make you feel like you just have 4 more levels to go.
New Classes
Cataclysm doesn't introduce any new classes to the game. Instead, Blizzard have offered more race and classes combinations to players. The Some of these have alreadly been datamined from the 3.2.2 Test Realms. The An Injured Colleague quest and it's new Night Elf counter-part help to introduce the lore for these new race and class combinations, so we can probably expect to see more of these for some of the less traditional ones.
* Human Hunter
* Orc Mage
* Night Elf Mage
* Dwarf Mage
* Blood Elf Warrior
* Dwarf Shaman
* Undead Hunter
* Tauren Paladin
* Tauren Priest
* Gnome Priest
* Troll Druid
New Races
The events of the cataclysm has caused two new races to seek new allies. The Goblins for the Horde and the Worgen for the Alliance.
Goblins
Deathwing once again sought the services of the goblins, as slaves. Unable to refuse such an offer, the goblins were enslaved by him. A large group have resisted however. With their previous homes devastated by the cataclysm, they escaping to an island off the coast of The Barrens. As they strive to recover, they come across an Orc captured on an Alliance ship and rescue him. The Orc turns out to be none other than Thrall himself, and in return offers the Goblins a place within the Horde. These events are carried out in a quest line, allowing players to experience first-hand the reasons behind the Goblins' shift from neutrality.
Worgen
The cataclysm has cracked open the Greymane Wall, finally revealing what has happened to the kingdom of Gilneas and its citizens. With the Worgen curse taken hold, they have found a partial cure, allowing thme to retain their Human minds even when transformed. Venturing forth from Gilneas and seeking help from the Alliance, they have decided to join them, to combat the new threats of Cataclysm.
Gilneas will make extensive use of the phasing system (much like the Death Knight starting area), to show what happened while the kingdom was cut off from the rest of the world and lead up to present day.
Worgens will have two forms, a Worgen form and a Human form. Players will be able to customise the look of both forms.
New Content
Cataclysm will be the first expansion not to introduce a new continent, instead making use of previously unreleased zones and revamping existing ones.
Classic Azeroth Revamp
A cataclysmic event caused by Deathwing and Azshara will change the face of Azeroth as we know it. Most of the new content for Cataclysm will take the form of a revamped Azeroth, taking advantage of newer additions to WoW such as phasing and daily quests. Most of the quests and mobs in the classic zones will also be redesigned to make leveling less painful. With the revamp, a greater narritive and sense progression will be offered to players. Some zones and dungeons will change drastically to fit this, e.g.,
* The Barrens will be split into two separate zones of two different level bands.
* Azshara will become a low level (~10-20) zone.
* Some of the zones like the Thousand Needles will be flooded.
* Durotar is wrecked and apparently Orgrimmar could be destroyed. A new Orc city is rebuilt over the course of the expansion.
* Gnomeregan will be part of the expansion as well and gnomes might be able to reclaim their capital. (The last part is still unconfirmed)
* Wailing Caverns will be become a lush tropical area as a result of the druid's magic.
* The Blackrock Spire will erupt and a new version of Blackrock Mountains will be available, apparently Ragnaros will be back too.
In the aftermath of the cataclysm, and the new conflicts on the horizon relief efforts can be found in many zones and new open PvP areas similar to Lake Wintergrasp.
Flying in Azeroth
Part of the redesign of the Eastern Kingdoms and Kalimdor is the introduction of flying to the two continents, allowing access to many new areas and quicker travelling across the large continents.
Classic Dungeon Revamp
Redesigning Onyxia's Lair in Patch 3.2.2 was just the first step. As most of the leveling will take place in revamped areas of Azeroth, so too will the dungeons, allowing players to use them to level from 80 to 85.
Unreleased Zones & Dungeons
With the addition of flying mounts to Kalimdor and the Eastern Kingdoms and the redesign of many zones, most of the previously unreachable or incomplete zones will now be made available to players. This is where most of the new content from 80 to 85 will take place. Some of these are,
* Hyjal (present)
* Gilneas - The Worgen starting Zone.
* Uldum
It is unclear if the old Goblin locations such as Kezan and Undermine will be included in Cataclyms with the revelation of the goblins' plight, but several new islands have also been risen from the seas by the events of Cataclysm, some on the backs of giant sea turtles and whales, with the addition of several underwater zones.
Characters and Events
Deathwing
Deathwing the Destroyer / Neltharion the Earth-Warder will play a major role in Cataclysm. Having been driven mad by Old God whisperings and turning against his own kind only to be fail in his attempts, Deathwing has sunk into the shadows. While the Horde and the Alliance were busy fighting back the Burning Legion only to then be beset with the Scourge, he has been lurking and moving things into place. After Lady Sinestra's failed attempts to create a Twilight Dragonflight, he again retreated to Grim Batol and succeeded where she failed. With his results seen in the Obsidian Sanctum, he has finally created the supreme Dragonflight he sought and plans to unleash it upon the world. But what of the Old Gods' sway over him?
Azshara
Queen Azshara will also play a major part in Cataclysm. Unknown to many mortal races, long forgotten by others, and believe to be dead by her own kind, she has not been dormant in depths of the Maelstrom. Having those around her transformed by the Old Gods into Naga after her failure in the War of the Ancients, she has become far more powerful and a greater threat than she once was. Not content with just Nazjatar and the depths of the sea, Azshara seeks to reclaim power and reign once again. With the true plan behind Lady Vashj's support of Illidan remaining a mystery we do not know what hand Azshara has yet played. The big question remains, is she now serving her "saviors", the Old Gods?
The Cataclysm
I'm still not sure who is the true end boss of Cataclysm is, but the cataclysm appears to have been caused by attempts to incantation to summon extremely powerful beings using an ancient incantation by Deathwing and Azshara. They're both very powerful, but the cataclysm itself suggests something more powerful is behind it, perhaps their shared past of Old God influence?
The Guardian of Tirisfal
Malfurion Stormrage will be returning to Azeroth to aid in the creation of the new Guardian of Tirisfal - Thrall! Med'an's role in these events is currently unknown.
The New (New) Horde
Thrall will hand over the leadership of the Horde to Garrosh Hellscream, while he serves as a coordinator for both the Horde and Alliance forces in and effort to combat the new threat of the Naga and Black Dragonflight. Without Thrall to keep Garrosh in check, he declares open war on the Alliance. In the political upheaval Cairne Bloodhoof is implicated as a traitor to the Horde and murdered by Garrosh. Cairne's son Baine takes over as the new Tauren chieftan. This could explain why Baine was removed from the game in Patch 3.2.2, you can find more information about this in Ahmo Thunderhorn - replacement for Baine Bloodhoof?
Та в тоя ред на мисли - всичко може да се очаква от Близард, ама ги разбирам. Просто се опитват да изстискат максимално Warcraft universe-a преди да бъде погребан и забравен, поне до излизането на IV. 
ЛоЛ умира... умира най жалко ... умира от недостик на оригиналност.
