Through each successive OS upgrade for the iPhone 4, I have continued to experience proximity sensor issues (a bit better on 4.1 than on 4.0.2, but the problem is still definitely there).
Are there others who experienced the issue with 4.1 who have since moved on to 4.2.1? I haven't upgraded yet and am stalling...
I had the issue in 4.0 and it was minimized greatly by 4.1. It didn't go away 100% and 4.2.1 hasn't changed anything. I still get it from time to time, but not enough to bother me.