How do I set up git so that I get a message through gchat or aim that someone pushed onto the server?

What do I need to set up the server so that I get an update message through gchat/aim? Do I just set up a client on the server and use a hook combined with a script?

You can use the .git/hooks/post-receive hook to inspect the new changesets and use a command line tool like sendxmpp to send the messages.