I really like the URLs you chose. They mirror the ones GitHub uses, and I think they'll serve us well for the forseeable future. If I had it to do over again, I might have stuck a "master" or something in the existing "source/..." URLs, but we missed that opportunity, and this is a close second. Actually, having the special case has a handy advantage: you don't have to type "master" if you just want the latest.