I could see maybe one retail and one indie a month as per 360, but I can't imagine giving away retail titles for a while yet. Sony said November time (iirc) for "better" (retail?) games on PS+.... Even that seems too soon for the relative lack of games available.
@nablett, I agree that it's too soon to offer full retail games. I don't see them giving away games like AC4, CoD: Ghosts, Battlefield 4, Dead Rising 3, Titanfall, etc.; some of the big games. I could see them giving away Rayman Legends, PvZ, Child of Light, Angry Birds, Crimson Dragon, Lococycle, Powerstar Golf, Peggle 2, Strider, MGSV: Ground Zeroes, Strike Suit Zero, Trials Fusion, etc.; some of the less costly titles.