GIT-Commiter is a project mainly written in Objective-C, it's free.
A Cocoa git commiter (although it allows you to clean and pull too)
Git commiter is a Cocoa app for commiting, pulling, and cleaning your commit. It's really easy to use, just a few clicks and you're commiting, pushing and whatever.
It may fail with some repos where when pushing asks for username and password. It's recommended to have public keys set up :)