I am surprised Apple doesn't implement some kind of authorization network for internet streaming.

Everyone's main complaint (including mine) is that they can't stream from work to home and vice-versa.

What if iTunes had a VPN in it? Apple could set it up so that you could stream from any iTunes that was logged into your iTunes Music Store account to another iTunes that was logged in. The applications could share a "key" to authorize the stream. Apple could use the 3 machine limit here as well. Having 3 machines logged in is fine...and subnet streaming would be unlimited.