Makes me wonder what the best way to track your phone would be. If the device is stolen and the thief connects to the internet, the N900 could be prepared to notify the original owner about its location and maybe send pictures of its surroundings, ideally triggered by entering the wrong unlock code (which of course requires it to be set by the user).

I personally have my phone configured to connect to my openvpn server at home by default and use sshfs to copy files to and from it, as this way i can access the phones memory wherever it gets connected to the internet as the ip adress of the tunnel device stays the same - amazingly one can even change from wlan to 3g while copying files using sshfs, just some short freeze while the tunnel reconnects. It's not as fast as usb but it's very very convenient.
I now realized that if my phone would get lost, I still could connect to it and would have shell access (i'm pretty sure there would be a way to retrieve gps coordinates from the shell), however setting up a openvpn server is not what everybody does in his spare time, so I wonder if there is another, more easy way to keep the phone accessible from remote, or at least let it connect home in periods.

A dyndns client for the n900 might do the trick, if there is also an ssh server running on the device. If there is interest and it's not yet existing, I'd try compiling some dynamic dns client. Not sure how the different interfaces get handled, but i think it should at least be possible to make the device remote accessible when it connects to wlan.