Ninja Gaiden II has been out for a few days, and the demo recently came to USA and Canada (downloadable over XBL). Much better than Ninja Gaiden Black (can't compare it w/ the original, since I don't have it). Very gory though (cut off an enemies limbs, sometimes they'll throw them back at you depending on the enemy). Recommend the demo to anyone who enjoys ninjas and isn't put off by extreme violence. Videos really don't do the game justice, try it for yourself.
EDIT: Oh yeah, and I think it's an Xbox 360 exclusive.