Samsung has just dropped the source code for the Sprint version of the Galaxy S III, and it's available on Samsung's open source web portal here. Samsung has been surprisingly on-point with getting source code for the Galaxy S III here in the US, ensuring that custom kernels and ROMs will have the maximum amount of tweakability available to tinkerers from the likes of RootzWiki and XDA.
Samsung has released the source for the Fascinate, roughly a week after the phone was released. As usual, any bits that are special to Sammy aren't included in the release, but there should still be enough material in there to get tinkering. As I've said before, the layperson doesn't really benefit from the release, but modders can get down and dirty with the code to tweak things just the way they'd like - and hopefully, make those changes public so that others can get in on the action as well.