Fusion is a newly released tweak, which does something pretty special. Using the inbuilt ‘Quick Compose’ iOS 5 functionality of Twitter, Fusion allows you to send messages, pictures among other things, to 4 social networks in sync. These networks include (Facebook, Twitter, Myspace *insert joke here* and FourSquare. It does this in a very efficient fashion, and works exceedingly well. It even has a assistant extensions plug in, so you can use fusion with Siri!
You can pick up fusion in the BigBoss repo, for $2.