Ever since the G2 came out, hackers everywhere have been throwing their extraordinary talents at finding a way around what some have called a "root-kit" virus that comes on the phone. It appears that the G2 has a new type of security measure built in to it that essentially thwarted all attempts at acheiving a permanent root status on the device. That is until now.
As we all would expect, a method to permanently root the G2 has been posted on the XDA Developers forums. Forum member unforgiven512 has created a guide for acheiving the unacheivable. Although the process isn't extremely complicated, I would recommend only users with a moderate amount of experience attempt it. You'll need to be familiar with ADB and working in a terminal window to complete the steps. There is also a definite amount of danger involved with it.
Unfortunately, I don't have a G2 available currently to test with, however, the posts in the official thread at XDA seem to confirm the success of this process. If you're willing to take the risks, then by all means give it a shot and let us know how it works out for you.
Source: XDA Developers