Raptr, a social network for gamers, just released an iPhone app that makes it even easier to track your friends' gaming habits on Xbox Live, PSN and Steam. It's a pretty nice way to keep in touch across platforms.
You'll need to get a Raptr account to start but you can sync it up with your Xbox Live, PSN and Steam accounts to get all your gaming friends and their updates displayed in one stream. For Xbox Live users, you can even send and receive messages to your friends (which is way easier to do on the iPhone than on the Xbox controller). If you game regularly on multiple platforms, give Raptr a try. Free. [iTunes via TUAW]