As previously reported, you can pick two PS3 games from a list of five (Infamous, Dead Nation, LittleBigPlanet, Super Stardust HD, and Wipeout HD), plus two PSP games from a list of four (LittleBigPlanet PSP, ModNation Racers, Pursuit Force, and Killzone Liberation).
The free games will be offered through July 3, but as long as you claim them before that, they'll be yours to keep. To claim them, go to the Welcome Back section. You'll pick one game from the section marked "Game 1," then go back and select another from the section marked "Game 2." If you own both a PS3 and PSP, you get four games out of the deal.
Plus subscriptions have been added or extended, 30 days going to non-Plus members and an extra 60 days going to current Plus members. A selection of movie rentals will be available over the weekend as well, and Music Unlimited subscribers have had an extra 30 days of premium service added to their accounts. Sony also promises that publishing dates on missed content will be coming soon.
You might want to wait a little while to start claiming your free stuff, though. Various users are complaining of errors accessing the Store, apparently due to the deluge of users rushing to grab their free content. Among those who have made it in, some are getting connection interruptions mid-transaction. There are mixed reports of a workaround for lost games through the Account Management listing, and Sony is sure to get any problems sorted out. At the same time, it doesn't hurt to have a little patience.