This cross-compatibility hinges on Steamworks, which the PS3 version will include. So far Microsoft hasn't decided if they want to allow it on Xbox Live.
Getting co-op to work between PS3 and PC gamers of Portal 2 is “something the team is gunning for,” revealed Valve’s Eric Johnson, reports . "The plan is you will be able to play between console and PC," echoed developer Mike Dunkle.
Boss Gabe Newell announced this week at E3 that Portal 2 would be coming to the PlayStation 3 as well as Xbox 360 and PC. They all launch the same day next year. Got some friends in the PS3 camp you think will make a good enough ally?