Legal P2P, part 4

One topic I wanted to discuss was the topic of recalls. Consider this: What happens if you suddenly feel the urge to listen to your song, when somebody has it borrowed. In the basic system I have described so far, you would be out of luck. The best you could attempt would be to try to find the user that has your file checked out but it would not be garanteed that you could find him.
There are some solutions though:
The most obvious one would be to borrow somebody else's file. You could request a short borrowing cycle, or a longer one.
If we moved to a centralised system, the main server could receive your recall request and execute it when it would find the person that has your item checked out.
The third solution would involve DRM: all songs could be encoded with DRM that would "phone home" everytime a file needed to be played. This way, you could revoke the license of the person that borrowed your file and wouldnt have to worry about the other person connecting or not connecting to the network to respond to your request.