Valve has announced their plans for a second Portal 2 DLC release. This time Valve is working on a level editor that will allow players to design and build their own test chambers. Creators will then be able to share their levels with other gamers. The DLC will also support the ability for players to provide feedback via reviews of levels.
According to the press release provided by Joystiq, Valve stated the level editor will allow the design of both single player and co-operative maps and is intended to be very user friendly. At this time, the DLC is confirmed for PC only, but it may later show up on the PS3 and 360. Since the PS3 actually has Steam and the cross platform functionality, it seems to me a no-brainer that this DLC pack will end up there, but that is only speculation at this time.