Major Nelson announced that the "My XBox LIVE" app is now avaliable for iPhones, iPads and Android phones. The quick thing to point out is that isn't the Smart Glass app that was teased during E3, but it could be considered a distant relative. More like Homo Erectus than your Uncle, though.
The updates to iOS allow iPhone app users to "[c]onnect to and control content on your Xbox 360" along with managnig your avatar, and achievements; "The new Discover section will let you find fresh entertainment through your phone to play on your console. You can also access on your phone a quick list of your most recent console activity," Nelson, or as some say Hryb, wrote.
The Android release, so far, has what the iOS used to: everything but the ability to effect the XBox Live. No idea when the Android app will be on par with the iOS.
The apps are free to download.