This was a great surprise to find when I got back from TechEd. You can now sign up for Xbox live alerts that get sent to your MSN Messenger account as a popup, or to your cell phone if you so choose, when you're not logged in. This is absolutely awesome because my buddies spend a lot of time on PC's and relatively little time on Xbox Live. Using alerts, I can try to track them down to whatever Counter-Strike game they're in and have a little fun.
MSN Messenger and Xbox Live Alerts
Imagine being able to get a game invite on your cell phone, as well as news about new games and downloads. How about being able to get the latest Xbox news and see which of your friends are signed into Xbox Live right in your MSN Messenger? It’s not a dream, it’s real, and it’s happening right now.
Of course, you might need to be a little careful with these capabilities. If your boss is one of your buddies, it's easy for them to keep track of your Xbox Live usage. We have an internal Xbox discussion where somebody mentioned that a couple of his friends were logging in between 3:00 and 3:30 in the afternoon. I pointed out that I have a couple of boys who hit the Xbox first thing after school.