Valve's introducing a beta Steam Mobile app for iOS and Android devices that lets users chat with their friends, see when they're online and what games they're playing, and browse news and other game-related information. It sounds like a fairly direct port of the full Steam platform, just without the ability to actually play games. You can "express interest" in the app now by downloading it, but it's a closed beta so you might have to wait a while to receive an actual invite.

Thanks, TheFaithfulVergin and Nincodedo!