Yeah, you should post the comments on snapfinch itself by default and then ask the user if they want to share the same comment on other services. So, if I logged in with Twitter, let me post a comment first and then ask me if I want to tweet it with a link back to the snapfinch page. So, you make it more social without making me jump through extra hoops.

Social is not about all these services; there will be ten new photo sharing apps tomorrow. It's about the people. Make it fun for us and and make us look cool and interesting to our friends.