From what I've read this is Fantasy Flight's first foray taking the Battlelore license they purchased from Days of Wonder and doing something with it. It's listed as a "Battlelore game", but from what I've read in an interview with FFG it's only tangentially related. It sounds like they'll be changing the mechanics quite a bit, I've heard some people say it comes off as a cross between Battlelore and Tide of Iron.
The first Core set is supposed to have armies for the Starks and Lannisters, with expansions adding more Houses later.
That's what I've heard too since making the initial post. I've read a review of someone who got to play an early edition of the game at the FFG event. It's definitely quite a bit different from battlelore. One thing that sounds great about it is that they did away with section restricted orders. It also has 8-sided dice instead of 6-sided. Some posters at boardgamegeek have said it more closely resembles Command and Colors: Ancients than Battlelore.