Mytouch 4G root

Even when they're relatively easy to root, it usually takes a few weeks of elbow grease to get an Android device fully opened -- but thanks to the hard work that's been put into the T-Mobile G2 root recently, its just-released sister device has been cracked already, too. Sure enough, if you're willing to put a little time into it, you can now break your myTouch 4G wide open, which presumably means it won't take long before we see some stock ROMs become available (if you're into that sort of thing). Seriously, judging from the list of instructions, this isn't the easiest root in the world -- so unless you want to be up on the bleeding edge, you might want to hold out until some awesome ROMs start floating in. Then again, we totally understand if you do it right this second. We're the same way.

Exclusive from engadget
http://www.engadget.com/2010/11/10/t-mobile-mytouch-4g-rooted-has-g2-root-to-thank-for-it/