Rumors of a delay for Batman: Arkham Asylum, Eidos and Warner Bros Interactive have confirmed that the game has been pushed back. Speculation pegged the new date in the fourth quarter of 2009, and many thought that meant a definite holiday release. Eidos has now said the game will actually release at the "end of summer 2009," which means it has to release by September 21, still (barely) in third quarter.
The press release states that the additional development time is "to ensure Batman: Arkham Asylum is of the highest quality for gamers." In other words, it's probably about bug squashing and polishing up the game for release, not to mention taking advantage of the high anticipation by hitting just before the holiday release window.
Still can't wait for this game to come out...But hey check out the video preview from gamespot.