I find this idea very attractive! Maybe not for media sharing (I run ADSL, and maybe upload speed is not fast enough for video streaming) but for remote house control.
With the VPN running, a vpn enabled router and a hardware ip to X10 (or any other protocol) controller, It might be possible to remote control your holiday apartment lighting, heating or window blinds, or even have IP cameras connected to your main LMCE setup in that apartment that would trigger an alarm in your daylife home. Would this be possible?
Anyways, for those willing to have a remote MD on the other side of the tunnel, it might be necessary a HD based media director, Installing or starting a diskless MD through a VPN would take a lot of time to start.