I have my Palm TX connected to the Internet via Bluetooth, blackberry 8800 and T-Mobile. Its a tad tedious but I ran though the configuration twice and it works well. A "TMobile Internet" plan is, as far as I can tell, only needed for VPN access. I have access/control over two T-Mobile accounts so I was able to test things with various services enabled/disabled.
The configuration actually comes from an old Linux PPP configuration I developed and ported to the Palm. So I suspect Linux/Mac may be able to use the same approach, but I ran out of time to test Linux today.
I documented everything at my experimental web area
If anyone wants to reformat the document and add it here they are welcome to, just provide the customary credit/links to the original document. I do not have time right now to reformat it. I tried to post to the Laptop HOWTO thread but it seems to be locked, at least for me. Plus, I am not sure just how useful or applicable this is to any unit besides mine (Unlocked 8800 on T-Mobile).
Hoping this helps others, I will monitor this thread for questions and feedback.