dnlcllns,
I am fairly new to rooting Android phones, but I am pretty sure that currently, going from Android 2.1 to 2.2, you have to use a rooted rom and install it. There are various tutorials for doing this. Alternatively, you can get a Nexus One that's already got Android 2.2 and wait for a proper rooting method to come out for that.
There's also a program called Easy Root which costs $.99 which roots many phones. If used to be in the App Market, but Google removed it. The authors website has it available though and you can pay via paypal.
What I'm going to do now that I'm at Android 2.2 FRG01B is wait for the OTA update FRG22 and then root with whatever technique is developed. This is typically the safest approach.
