Here in my office I don't use Bluetooth, but my truck has bluetooth built in the navigation system.
I normally get about 5 or 6 calls a day in my office on my cell. And yesterday on every call I have hung up on, placed on hold or tried entering facetime chat every call I was on as my cheek hit the screen while talking.
I have NEVER had that issue with any of my other iPhones.
Scott this seems to be a firmware bug in IOS 4 as their is report on the web with the 3GS having a lot of the flaws stated with the new IPhone. So far me and my girlfriend have not run into these problems. Look for IOS 4.01 to be out within the next month with a fix to these problems.
IOS4 Is not ready for primetime yet and I believe that apple knew this and released the firmware early because of the IPhone 4 release.