If you have my.t-mobile.com account, the next you log into the site, have a look at the top right and you may just see a picture of the upcoming T-Mobile G1 (also known as the HTC Dream). Unfortunately, the link does not work at this time but all should be revealed next week.
If squinting at a small picture is not your thing, new and quite clear pictures of the T-Mobile G1 have surfaced on the web.
Source: Engadget