I've been using my Android Dev-1 phone on T-Mobile for a while now. I've had the T-Mobile VPN service which is useful if you need to do non-trivial connectivity things with firewalls and VPN software. For some reason, in the past few days when I try to go online, I get a blocking web page that simply says "Your data plan is not compatible with the G1" and then tries to sell me an "upgrade".
I checked my APN settings and they're all correct, I'm going to see if my Internet still works in my other phones, or if all my mobile Internet is broken. I'm going to be pissed if T-Mobile is playing shenanigans with the G1.
I checked with my Motorola Rizr Z8 and Internet works just fine. That means T-Mobile has done something "special" for G1 phones. Yeah, that's bullshit.