From a Danish forum I was able to obtain info regarding the marketing concerned with the release of the next WoW expansion. Alledgely someone involved in making banner commercials for large portals on the internet has been approached by Blizz marketing who wants them to have something ready to be posted from Nov. 1st this year and last until x-mas this year.
Accordingly this should mean that they plan to release the game no later than feb. 2008 and posibly even for x-mas.
I hope you guys are as excited about this news as I am :)
The article I'm linking to is in Danish unfortunately, but this does not change that the OP of the page is giving a 1st hand account of this "news".
Edit: English Translation Added - Nimloth
I have a friend who works in a media agency that handles banner advertisements for various larger portals in Denmark.
He has informed me that they have gotten an inquery regarding the launch of WotLK in Denmark and running advertisements on Danish sites from the 1st of November until December 24th.
He also says that the expansion is slated to be in store shelves somewhere close to Christmas 2007, with the latest release as late as February 2008.
Personally, I think that this is pretty fast considering It hasnt even been a year since Burning Crusade was launched. But who knows, money makes the world go around and the christmas sales revenue is something everyone wants a piece of!