MobileMe iDisk is an app that lets Apple MobileMe subscribers view or share some files stored online from an iPhone, iPod touch, or iPad. And without really making a big deal out of it, Apple recently flipped a switch that lets you use the iDisk app to stream audio files from the cloud to our mobile device.
In other words, you can upload music to your iDisk and then launch the mobile app to listen to the music on the go. This could free up space on your iPhone while still allowing you to access your music collection — or just provide a way to access your music collection on multiple devices.
The app allows you to stream music in the background if you’re running iOS on a supported device like an iPhone 4, iPhone 3GS, or newer iPod touch.
There’s no support for playlists yet, and you have to drag songs to iDisk one at a time or one folder at a time. And you only get 20Gb of storage space.