The next expansion patch (expansion pack 3) has not yet been unveiled (though it is stated to be 6 months into development as of August 2008).
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November 11, 2008 (Wrath of the Lich King)
The latest WoW patch, 5.2.0, and is known as the Thunder King Patch. The patch brings a massive new zone, a new raid, server-wide events, new factions and new world bosses.
It came out July 28 2009.
A patch mirror in WoW is a common element for that whenever a new patch is released for the game, it can be downloaded from different sources. One popular place for the patch is DepositFiles.
Official wow patches are applied automatically, there is no way you can NOT download the patch. If there is a patch available, the client will update itself. If you choose not to update, you will not be able to play.
just delete that patch in your wow client folder
Sometimes when you click on WoW, and log into your account it says new patch, and it loads to 100% then turns off WoW and opens a mini tab that shows the patch being downloaded.
It's coming out this summer. YEAH
It should be automatic. If it's not for you I recommend blizzard's help page
Patch level 3.2 for WoW has already come out, the present patch level is 3.2.0.10314.
Cataclysm Patch.
Start your WoW game like normal and Blizzard downloader should automatically start downloading the Latest patch.
You can just delete the patch file once downloaded and installed by wow. You can not revert wow to a previous version because wow is auto-updating. Every client has the exact same version (for their OS).