Oh Double Helix, why do you tease us so with pretty things we can't have yet? During the Play XBLA livestream on the 16th January (which is archived here), the team gave away some interesting tidbits on new character Spinal and other updates and fixes coming soon to the game.
The team have promised that owners of the KI Ultra Edition will receive Spinal sooner, and that he'll bring with him 15 new achievements for a total of 150 Gamerscore. They also mentioned that he'll handle very differently to the other characters, and that when playing against Spinal you'll need to pay very close attention to all your bars. Sounds like he's a leech character, then.
Double Helix also revealed that the implementation of online lobbies has been delayed until March. You might remember that March is also when Double Helix is scheduled to release the game's much-anticipated arcade mode, as well as its second DLC character Fulgore. Got to say, I'm not hugely confident all those deadlines will be met at this point. Of the arcade mode, however, the team said that Double Helix and MS Game Studios are writing the story, and that players will find a lot of fun lore and "neat things" in keeping with the original Killer Instincts.
We also learned during the livestream that the game's free character will change weekly instead of every couple of months. There will also, apparently, be new accessory packs every week. Enough to keep you waiting until March?