Twitter actually played a notable part in taking down several repressive regimes over the past year or two. I no longer trust Twitter to be reasonably available to the oppressed in a year or two, given their crackdown on third-party clients (like mobile clients). App.net is intending to be a platform for everything, and "everything" includes "bringing communication and openness to purge corruption out of the darkest corners of the world".

Yes, "everything" also includes "taking hipster photos of my meals and sharing them with my hipster friends", and that's closer to why I actually signed up, but the implicit claim that $50 towards a project as ambitious as App.net does _nothing_ to solve the world's social ills is very questionable.