http://blog.us.playstation.com/2011/04/13/valve-reveals-portal-2-for-playstation-3-steam-details/
"Steam makes its appearance on the PS3 as an overlay within Portal 2. Here, the Steam overlay provides access to Steam Friends, displaying their in-game or online status and providing a quick pathway to text chats, player profiles, friend requests, and game invites. Steam Achievements are earned in lockstep with PSN Trophies and are also accessible within the Steam overlay."