Before you upgrade to Diablo, make sure you feel comfortable with a little bit of work in the shell. Here's the wiki page that shows how to set it up:
http://www.internettablettalk.com/wi...tle=Diablo_PAN

Did you find the maemo-pan package? I'm not sure if it's in a separate repository or something. It also probably requires you to add some non-standard repositories to a new Diablo install. Just want to warn you it might be a bit of work if you're not used to mucking around with the tablet

In order for maemo-pan to work, you need your phone to be set as the default in the Phone section of the control panel. I haven't had any problems with my Blackjack, but I'm also using WM 5.

Oh, did you start the connection sharing app on your phone? It's kind of hidden on WM 6 phones, if I remember correctly. You can probably find the exe name online and add a shortcut for it if it's not there already.