Hooray! It works!
T-mobile doesn’t have the 5.99 tzones plan anymore. They upped it to a 9.99 plan. Don’t get rid of your 5.99 plan if you still have it!!! But the tzones hack still works. To get it working on your G1, check my post about getting the MMS to work without having a data plan here.
Then go into your test settings and change the data method to WCDMA preferred or unknown. If you get connectivity errors, you can goto settings and select ‘use only 2G’. This also saves aloooot of battery.
If you want to tether your laptop to use the internet from the G1 check my post here.