If 4.2 doesn't fix it, it's going on eBay!!
I am on my 4th iPhone 4 due to this issue. The Genius' keep saying that it "must be a faulty unit". Really? My 3GS never ever had this problem even on 4.0. This is a joke. The funny thing is so many people who don't complain (like one of the Genius') admit they don't make calls that much. If I wanted an iPod touch I would have gotten one. Bought an iPHONE for a reason. I just get tired of friends, co-workers, clients making fun of my phone or joking as they say "well you see, I can make phone calls with my phone".
I will wait until 4.2 and see if there is any improvement. If not, this thing is going on eBay.
- one thing that I have noticed that "helps" is that if I use the Black Bumper, I don't have as many issues. I tried a white Bumper as well as no bumper and it is almost un-usable. Not sure if the light is seeping in on the side of the glass or what, but let's face it, iPhone 4 is a beta product.