Update October 11th - Apparently the FAQ was removed today ... I guess we'll hear more about this during the week ...
Update - Just to clarify, this is directly taken from http://eu.battle.net/faq/index.html, the US version (here) doesn't seem to have the updated information and the process might be different on american servers. You might end up getting the old FAQ when checking the EU site, logging in fixed the problem for me.
Non Battle.net Accounts offline on November 12th
Apparently, if you didn't merge your WoW account to a Battle.net account you won't be able to play the game after November 12th. The good news is, you get a free penguin!
The penguin will most likely be Oswald (also known as Mr. Chilly, he was renamed in the latest PTR build of Patch 3.3 but Oswald is a nice name too), Mr. Chilly was the pet given to US beta testers who converted their account to Battle.net when the feature was on WotLK beta servers. Please note that Pengu was also changed in Patch 3.3 and doesn't have his scary red eyes anymore.Originally Posted by Blizzard Entertainment