Hi all, I searched first but didn't find any mention of this. Maybe this will help out someone else who did what I did.
I upgraded a couple of 1st gen phones (8gb and 4gb) from 1.1.4 to 2.0. They had been unlocked, so to be conservative, I restored them to 1.1.4 first and then upgraded to 2.0, and did not let them restore from backup (which seems to cause mail problems), and manually reentered info. The phones are now on ATT so don't need to be unlocked or jailbroken.
However. I had gotten the 2.0 from a sneak preview link which did not warn that there are TWO versions of the 2.0 firmware, one for older phones and one for 3G phones. And when I did the option-restore (using a Mac) and chose the firmware file, iTunes didn't check to make sure it was the right firmware for the hardware.
Firmware for old phone is named iPhone1,1_2.0_5A347_Restore
Firmware for new phone is named iPhone1,2_2.0_5A347_Restore
The 8gb phone was working, but having some issues with apps not opening and some crashes. The 4gb phone gave me more trouble with the update--the phone went into continuous-reboot mode, and I had to try the install several times before it took--and even two days later, it won't receive calls, which could be an ATT activation problem or could be a result of the wrong firmware, since the 4gb phone is several months older than the 8gb.
I just downloaded the correct firmware and restored my 8gb phone and will do the 4gb one as soon as its owner comes back from a trip. Hopefully the re-restore will fix some or all of the problems.