Yay! Thanks to this page, I managed to get a working GPRS connection under Linux (Ubuntu Hardy Heron). The only thing I had to change was to delete the line OK 'AT+CGDCONT=2,"IP","btmobile.bt.com"' from the /etc/chatscripts/bluetoothconn script. Also, the script /etc/init.d/bluez-utils was in fact named /etc/init.d/bluetooth. And the blues-pin package was apparently not needed (I couldn't find it anyway).
This all means that I: 1) had something to write about in this new blog of mine, and 2) I'm writing from the middle of nowhere, but it actually works, and is even not too painfully slow. Hooray!