Just found by Eurobricks’ whung on TLG’s official image cache, it’s the 10221 UCS Executor-class Star Dreadnaught! This is the only picture we’ve seen so far, but it looks amazing from this view. No price or part count is known. Minifigs appear to be Vader, Bossk, IG-88, Dengar, and what I’d assume is Admiral Piett.
UPDATE: TLG removed their image, so here’s a link to the one from FBTB.