Gamasutra has an excellent interview up with a company called Red 5 Studios. Their CEO, Mark Kern, served as a former team lead on World of Warcraft (though it's been a while -- since a little less than a year after the game's launch), so WoW fans (and Blizzard themselves) are curious about what the studio is up to. Unfortunately, they're staying vague at this point -- while they are definitely working on some kind of fantasy MMO, they're not exactly forthcoming about what it'll be.
They do say what they're not -- "we're not trying to be a sequel to WoW," Kern says. And they don't consider themselves in the same areas as Warhammer Online and Tabula Rasa, two games that showed promise earlier this year but never broke out as their developers expected. Instead, they want to do something different with the MMO idea, but as for specifics, don't hold your breath. They don't have a business model planned out quite yet, and even the game's announcement is "months" off.
So for now, we'll have to wait. It should be interesting to see what, if anything, comes out of the studio -- many people have said that WoW can only be topped by Blizzard themselves, and while having a history at Blizzard doesn't necessarily prepare you for making brilliant games every time (see Hellgate: London, created by former Diablo devs), it would be interesting to see if Kern (who has made his mark on WoW) can help Red 5 get another success together.