I have been playing around with the bluetooth on openSUSE and found this nice script that works very well.

It will make your phone a proximity card, and when you walk a certain distance away from your machine. It will enable the screen saver.
I use this at the local coffee shop all the time.

One tip is to pair the devices from the laptop not the phone.
hcitool cc BT:MAC:ADDR
or
hciattach --connect BT:MAC:ADDRR


Attached is my script, edit the MAC addr for your BT and adjust the time or proximity settings for your use.

Wow that's a slick bit of bash-fu, thanks! I just wish my stupid Thinkpad (ok it's not stupid, I like it) had BT builtin instead of needing a dongle, then I might actually use it more.

Oh now that *IS* pretty slick. I usually leave my bluetooth turned off to save battery life, but it definitely gives me some ideas...

An interesting reversal of the code could create a BB theft alerter! Say you're sitting in a cafe, leave your BB and laptop on a table to refresh the coffee. If someone walks by and swipes your BB you could have the laptop command play a really loud 'siren.mp3' sound or something instead of the screensaver.