ubermajestix
I graduated with a degree in mathematical economics from a liberal arts school and took some CS (Java and C++) along the way, but ended up not pursuing a degree because I could tell the technology being taught was outdated and largely irrelevant. I taught myself Ruby and Ruby on Rails mostly through reading books and blogs while trying to solve a problem for a client I was providing desktop support.
A friend's consulting shop recently hired their 20 year old intern b/c he is a great hacker, and he, in turn, dropped out of a CS program largely recognized as "very good" b/c it was he thought they were basically teaching "solved problems."
The point here is that a good hacker comes at any age, and your technical ability and attitude mater regardless.
I love working with the older guys b/c they have failed, a lot, and can steer me in the right direction and offer wisdom whereas I bring enthusiasm and an open mind.
Why would I want to contribute to someone's project that I don't even use? What would inspire me to all of the sudden want to hack on git's internals and then not dive into the source? On one hand, yeah, finding some menial bug or documentation fix I can work on to start contributing to a project is great, but at the higher levels just presenting tasks from issue trackers for me to smash, I don't think is a great idea.
Look at the ActiveRecord/AREL rewrite, sure @tenderlove was just squashing bugs in the Lighthouse tracker but only because, as he says, "AT&T Interactive started paying me to work on Rails" (http://engineering.attinteractive.com/2010/10/arel-two-point...) If you don't dive in real deep you can't really make things better and that takes a lot of time. You end up investing a lot in the project and the people around the project. So I don't see where GitHub doesn't support this. How does your product makes any of this any easier/better/more full of awesome?