I like the idea about motiviating people to contribute in a "musician-social-network". And the rewards so far are pretty sweet, especially when you bring some give-aways like T-Shirts (I like the "Swallow"-Shirt *hint-hint* :D ).
But I have two concerns about the whole system:
1) It seems to be "easy" to cheat the system. There seem to be some people spaming just random pictures they probably do not own by themselves.
2) If you throw in some rewards like shirts or so, please don't restrict them to US residentials only, like the guitars.