User blog comment:Lolzernator/Cross-Platform Co-op?/@comment-2121501-20100826235744

To be honest, I doubt it. 360/PC co-op has only been used a couple of times (the last one I can think of was back with the original Lost Planet), and never across 360 and PS3. I'm pretty sure the 1st parties are more concerned with selling their own version, so it's unlikely to happen