Although they don't make it clear, there are two versions of Vexed, a GPL game originally from the Palm platform, in the App Store. There was also a very short lived third version that appeared first, but was quickly taken down, mainly as I understand it, because of difficulties in complying with GPL and the Apple distribution model.
I am not a lawyer, so I don't know if the existing pair of Vexed applications are complying with that license or not. It wouldn't surprise me if they are not, though. There is no way to distribute source code through the App Store.