Not to disparge Wotmania (I used to know the guy that runs the site), but the Portalstone people, (whom I know fairly well), already mentioned this. In fact theories are flying.
This is the first I've heard about this. Since I work for the largest bookstore here in BR I'll have a look on the computer tomorrow ( I work 3pm - 12 am) and will post what I have found when I get home. The last few books in the series have been out in the fall though.
But to be honest I'm looking more forward to Martin's "A Feast for Crows" for his ASoIaF series and I still haven't seen a date for that yet but I expecting a late fall release for that one too.
It'll probably be out around November. That's been the pattern for the last couple of books at least. We find out the title around spring, and then the book finally comes out in the fall.
The first announcement I know of was a post to rec.arts.sf.written.robert-jordan by Teresa Nielsen-Hayden of Tor Books at 12:11 pm PST on Thursday 2/28/2002.
Since then, I've mentioned it on WotC's WoT d20 message board and here.