I recently went back to stock, so I could update to 2.1. (I used the youtube video below to do so.) When I did everything went exactly as said but I what I thought was weird is when it booted back up it kept my wall paper I had before and every app got removed except my BIC lighter app. I thought this was really funny considering I removed wiped the cache and did a factory reset.
Also, all my contacts were preserved viz Gmail, which is freaking awesome. +1 for google