The word going round is that T-Mobile is apparently considering offering customers free Gmail email access to those who purchase their new Google G1 Android smartphone.
Which means that if it goes ahead there should be no data plan or monthly fees to use the popular Gmail client which is obviously a bonus; although it is possible T-Mobile and Google could make it a free add supported client similar to the desktop version.
The word is if T-Mobile goes ahead it would be with some risk as a large part of their revenue comes via charging for data access which has become quite a large part of quarterly revenues.
Source — androidauthority