Android Guys has a story today from a
Turns out, of course, that it didn't work so well. When asked about it, T-Mobile customer service told him that the G1 will always access the Internet when it's on, even when the data roaming features are off (I'm presuming this is because of how closely the phone is integrated with your Google account), and that he should have left the phone at home to avoid the charges.
This seems bizarre; that the phone would continue to ping even when all data capabilities have been turned off. Has anyone else encountered something like this with the G1? Let us know.