The first game that will be given the PSN Pass treatment is Resistance 3, which will be released on September 3rd. The PSN Pass will be a one-time use code that will allow users to have full online access for the game. Sony states the PSN Pass program will be game specific, which obviously means games that they feel will have a big enough online component that will warrant them to stick a PSN Pass to in order to only allow players who purchased the game new, instead of used.
As of now, no other games have been announced to be included in the PSN Pass program, but if I were a betting man, I'd put money Uncharted 3 will be announced as being included in the PSN Pass program when we get closer to its release date. There's also no word if Sony will sell PSN Passes in their PSN Store for players who pick up a used copy and would like to partake on the online fesitivities for the game.