Since I started using git (and when using svn before that) I have always typed commit messages on the command line using the -m switch. While that works the usability is not exactly fantastic. The funny thing is that it is very easy to change. I do all my development on OS X and my text editor of choice is Textmate. With that combination it is just a matter of issuing the following command:
git config --global core.editor "mate -w"
This will also make it easier to abide by best practices about how to write commit messages.