It appears AT&T has found the root of the iPhone’s connectivity problem. (Hooray!)
The issue: the iPhone was requesting more power than necessary for the cell tower. If the transmitter is receiving signals from a vast number of iPhones asking for this overabundance of power, the transmitter will be sucked dry of all its power, resulting in dropped calls and other fun problems.
The "Bug Fixes" from the 2.0.2 firmware update was meant to limit the amount of UMTS power the iPhone requests. However, since not all users have downloaded the firmware update, the problem persists.
So the update was to curb the iPhone’s hunger for power. I think we can all sleep a little easier, knowing this. Although there still is that security issue…