Git is a very popular distributed version control system. You can use it to track versions of files in your project and collaborate with other project participants in very sophisticated ways. To learn Git, I'd recommend Scott Chacon's Pro Git book (free online, or buy a printed version). You can use Git on your local computer, but if you want to access it from multiple computers with Git installed, MobileMe can be handly.

Your MobileMe disk space is available via the WebDav protocol, which Git can also use. Here are the steps to create a repository on MobileMe. First, if you use Git from MacPorts, chances are that Git on your machine uses a version of curl without SSL support. In Terminal, use the following command to check:

$ port installed curl

If that does not list +ssl in the curl options, reinstall it by typing sudo port install curl +ssl. Once that's done, you're ready to set up your repository.

First, create an empty bare repository on your local machine:

 $ mkdir myproject.git
 $ cd myproject.git
 $ git init --bare 
 $ git update-server-info

Then, copy the whole directory myproject.git to your iDisk. I've copied my project into the iDisk root folder, but you can copy it anywhere on your iDisk. Now you need to add the newly-created repository as a remote to your local repository:

 $ cd myproject
 $ git remote add mobileme https://uname@idisk.me.com/uname/myproject.git/
 $ git push --all mobileme

Replace uname with your MobileMe username, and note the slash at the end of the URL -- without it, this will not work. That's all, now you can clone your repository using the above URL.

You can also easily make the repository public by placing it in Web/Sites folder on your iDisk. In this case, it will be accessible at http://web.me.com/uname/myproject.git. I haven't yet found a way to share the repository with only selected users, without making it all public. So some of the Git workflows will not be possible. However, with this setup you can use MobileMe to sync your repositories just as you sync email, contacts, and so on.