Sony’s welcome back initiative has finally been rolled out on the PSN store. Sony is offering a choice of two PS3 games from a list of five and two PSP games from a list of four. The program works on an account by account basis so if you have two accounts made before the outage then you can do what I did and grab almost everything being offered.
In addition to the free games Sony is also offering 30 days of Playstation Plus which gives you access to free games, discounts, and cloud saves for the duration of the 30 days. The network is being hammered right now by people attempting to get their free stuff, so you might want to try later. You can get more info and trouble shooting help over at the Playstation Blog.