Apple patent: access iTunes library from anywhere
This patent is for accessing your entire iTunes library from anywhere—streamed to your iPhone or touch either via Wi-Fi or EDGE/3G. Basically, this future iTunes will sync the metadata for your whole library, and all the music and videos stored back on your computer ("virtual media items") will be totally integrated with the content actually on your device, so it'd be just like having your entire library on your phone.
via gizmodo