I have had the signal fluctuation issue since 1.0 through 1.1.1. I also notice that I'll have 4-5 bars during a call, then when I end the call, the phone drops to 1 bar and loses EDGE. Most of the time reception returns on its own, although sometimes it takes a while.
In fact, I took a video of it to show the Apple store genius. Unfortunately, he said there was nothing he could do to help, and he directed me to AT&T.
http://www.youtube.com/watch?v=Z1q24ftCg0M