a serious git extension that slings out commit messages for you, broceptor.
Windows
C:\path\to\Git\libexec\git-core
Linux
/usr/lib/git-core
Mac
$ git --exec-path
Then drop git-bromit into that directory.
e.g.
$ /Applications/Xcode.app/Contents/Developer/usr/libexec/git-core/
when you are ready to commit:
git bromit