Every version of Portal 2 for every platform will be the same "in content" according to Valve writer, Chet Faliszek but fellow Valver Erik Wolpaw begs to differ. Mr F' states that, "When you buy them they're all the same." We hope that they'll be the same after as well. Not quite, "It's just once you start looking at co-op. The Mac, PC and PS3 can all play together, they will all get updates quicker. For some people that will make a big difference."
He continues, "They're all exactly the same. Content-wise, you're getting the same experience in them."
Except things then get confusing when Valve's Erik Wolpaw piles in with, "If playing cross PC and PS3 is important to you, then pretty clearly it's not even a matter of opinion. PS3 is the one to get."
"On PS3 you get the cross-platform play, you get the frequent updates," Faliszek explained. "The frequent updates allow a lot of things. They allow the cross-platform play to happen. You get the Steam cloud. So if you're playing a PS3 over your friend's house, and play on his PS3 the save is recorded.
"You also get the Steam copy. It's not a copy we just give away. It's attached to your PSN and Steam account. But yeah, there are some cool things you can do there."
Source:
EG