Well for those of you that want to go back to stock 1.5 or 2.1 here you go. Not sure if this was posted already, I looked and didn't see it but you never know if you miss something. I read through how to do it and it is as easy as flashing a rom. So flash a rom to unroot I guess.
[ROM][9/25/2010]FlashBack15 v1 -Return to Factory Stock - xda-developers
[ROM][9/25/2010]FlashBack15 v1 -Return to Factory Stock - xda-developers