You will need a Steam account for the full Portal 2 experience on PlayStation 3, Valve has revealed.
PlayStation Network accounts can be linked to either existing Steam log-ins or freshly created ones.
Once the two accounts are joined, PS3 owners can enjoy cross-platform matchmaking and co-op play with Portal 2 gamers on PC.
There's also cross-platform chat, Steam Achievements (earned in synch with Trophies), player profiles and game invites. You can even play Portal 2 on a PC or Mac - Valve grants a free PC/Mac Steam edition of the game to PS3 gamers.
Portal 2 arrives next week.
"An hour messing around with Portal 2, then, is enough to change it from a pleasant prospect to a truly unmissable one," wrote Christian Donlan for Eurogamer earlier this year. "With some promising new ideas and some great old ones, Valve shouldn't have too many troubles enticing people back to its mean-spirited geometrical playground."