Yes, I upgraded my iPhone 2G from 1.1.4 to 2.0 using PWNAGE 2.01 yesterday.
The Mail app crashed initially and I had to SSH in and change the ownership of the Mail folder. All fine now.
Set up Mobile Me with no problems, first on iTunes and then on my Mac and then on the iPhone. Any changes made to the calenders, contacts etc are pushed through to all devices...
It seems a bit buggy, sometimes it crashes from the contacts back to the home screen, but it works by and large.