As part of their now yearly Summer of Arcade promotion, XBLA will be getting a new exclusive(perhaps timed) 2-D Castlevania game called Harmony of Despair. Of note is the online co-op mode and competitive online multiplayer mode entitled Survival Mode. I'm not sure how thats going to turn out but it sounds interesting.
As a side note, all three systems(including the PS3 and Wii) continue to get really good exclusive downloadable games. I told myself at the beginning of this gen that I would rarely(if ever) support DL only games because I prefer to have a physical disc, case and manual. But Microsoft, Sony and Nintendo are making that damn near impossible with all the great XBLA, Wiiware and PSN games they keep releasing. Atleast hard drives are getting bigger.