Seems the cover art TSS posted a few weeks ago was right on the money: not only was it the final cover art most versions of the game, but Rare’s legendary platforming (and driving) duo, Banjo and Kazooie, are in!
SEGA has just now released cover art for all versions of the game, and the 360 version has something special:
No word yet on how this effects the 360 version’s roster, though it’s worth noting that no other versions of the game have an exclusive character featured. You can see the rest of the covers on the game’s page. This is more then likely the big ASR announcement SUMO was talking about, though nothing has been confirmed.
Special thanks goes to Shadi Wulf for bringing this to my attention.