I have an AT&T nexus one and before I upgraded it I think it was running EPE54B or something similar and the upgrade (Froyo 2.2) is intended for T-mobile phones which run the ERE27 and so what you need to do to get 2.2 on an AT&T nexus manually is:
1: Unlock bootloader [using fastboot] (so you can install a custom recovery "flash")
2: Install a custom recovery flash I used: recovery-RA-nexus-v1.7.0 (so you can install custom roms such as this and bypass a signature verification)
3: Flash This
Dang we are still waiting for the update for AT&T Nexus Ones? What's taking you so long Google?
This has nothing to do with ATT. Remember Google has not even released froyo for ANYBODY yet, including the t-mobile version. Somebody just happened to find the froyo update link for an early release, so everyone started installing it. There very well could be an ATT version on a server somewhere but nobody has "found" it the way they did for the t-mobile version.
No, Google actually did release Froyo OTA to a few T-Mobile Nexus Ones.
To developer and press phones, yes. Not to the general public.
Was I wrong?