<edit: disregard unless you're a hackintosh user, this belongs in OSX forum>
I've managed to get Bluetooth tethering to work w/ my Nokia 5800 expressmusic. However, upon reboot, it never works, giving me an 'bluetooth serial failure' error 'failure to open RFCOMM serial port'.
THe device is paired and I've checked in my phone its set to allow connections automatically.
functions (file transfer, isync) continue to work fine.
If I delete all settings and add the phone again in bluetooth, re pair etc. it works fine. Until the next reboot (but file exchange, isync continue to work).