I used rom manager to flash 2.2 very easy to use and I was able to backup my 2.1 in the process.
If this had been posted already feel free to remove.
I updated the same way.. I was surprised at how easy it was and wondered why more people don't go that route.. As far as backing up 2.1, how do you restore? .sbf and then restore after.. I found out the hard way you can't restore while 2.2 is there..
Yes it does. Just have ROM Manager and the Bootstrap app installed and you can use ROM Manager to backup and restore nandroids and upgrade to 2.2 with it for those who haven't. I don't think you can install any other ROMs just yet though. For now it's just 2.2.