Interesting - I didn't know you couldn't submit GPL-licensed code to the app store. It's surprising to me, but I can imagine a legal reason why it could be difficult for them to support. Still, seems like it should be possible.

But GPL isn't the only kind of open source. In fact, it's an extreme form. I've spent a lot of time contributing to open source projects, but I stay away from GPL, because they are really limiting in what you can do with them.