Valve has sent out a press release that lists all the Steam support PS3 users can expect to find when they pick up Portal 2 next week.
First and foremost is the cross-play feature, allowing PS3, PC and Mac users to play online together in the game’s co-op mode. Don’t forget that if you pick up the game on PS3 you’ll also get a free copy for either Mac or PC so you’ll be able to try out that cross-play for yourself.
Steam Cloud is also implemented, allowing players to save their new PS3 games to the cloud and play them on any other system without the need for a PS Plus account. You’ll also be able to look at your Steam friends via PS3, starting up text chats and inviting each other to games. Plus, any trophies you earn will also unlock as Steam achievements.
You can create a Steam account on PS3, too. Valve are being mighty generous with all this content so be sure to send them a big thank you card when you purchase Portal 2.