Hooray for XDA! XDA Developers forum member unforgiven512 has just posted a comprehensive list guide on how you, too, can permanently root your T-Mobile G2. It's scary, it's hairy, and it can permanently brick your phone FOREVER, but the riches are also at your fingertips. This guide is based on the work of forum member scotty2, and takes you through the process of rooting your G2 step by careful step.
As the folks over there at XDA say, this is a major achievement, and deserves some applause, as this is a goal the developer community has been going after since the release of the device. Now REMEMBER THE FOLLOWING: this is one of those times, even more than other times, that I and all the people in the rest of the world must warn you to be careful. DO NOT do this rooting unless you know what you are doing as ONE MISTAKE will permanently brick your phone.
In other words, JUST FORGET IT ALTOGETHER! In fact, instead of doing this, head over here to the G2 Review we did. Much safer. But if you're adventurous and cannot be swayed, go over to the XDA forums and get your fill.
[Via XDA Developers Forum]