I asked a T-Mobile data question yesterday in this thread:
http://talk.maemo.org/showpost.php?p=321263&postcount=8

Are N900 users going to be required to have voice plus data, or does anyone know of a data only plan for just mobile web consumption sans voice. Something like $30-ish per month I would presume.

I haven't spoken to T-mobile directly, but was wondering if anyone knew any details about it. Thanks.

Joe