If you're a big Mutant Storm or Geometry Wars fan, you're probably already in the process of downloading this, but just in case... The mind-melting co-op shooter, Schizoid, was placed on XBLA today. Created by Washington-based studio, Torpex, it's a hallucinogenic melting pot of danmaku madness, with two players working together to destroy merciless swarms of enemy craft. Participants choose either a red or blue craft and can then only destroy baddies of the other colour. Hence, close co-operation is the very essence of survival ('Live together, die alone' as Jack Shephard might put it).
Schizoid is, famously, the first XBLA titles to be completed using the XNA Game Studio SDK - a mouthwatering hint at what is to come from this Microsoft initiative, which is supposed to mutate into a community publishing channel (more details here).
By the way, Torpex technical director, Jamie Fristrom, also writes the illuminating Gamedevblog, which is definitely worth a look if you're interested in indie-flavoured development.