I really liked what Forgetfoo did with his Comment Notifier and I was planning to get mine out before he wrote about it but our server was down yesterday due to maintainance. So, I had to wait with the server side implementation until tonight.
My solution tries to mimic the popup notifier that MSN Messenger introduced. Basically it checks once every minute and sees if a new comment has been added. My solution ended up being more or less a copy paste from the previous experiments I did with Tunage.