So I rolled the dice and installed the 2.2 update last Friday. It went smoothly and for the most part I really didn't notice much difference over 2.1. On Saturday, I was out of town and in spotty coverage, and when I checked the phone at one point I saw that I had a couple text and voicemail messages, and missed a couple calls, but the phone never gave a notification or sound. I wasn't sure if I just didn't pay attention, or if it was due to the spotty coverage, so didn't worry about it. On Sunday, as I was driving back home, I tried to make a couple calls and wasn't getting any sound during the call. My wife said she could hear me, but I didn't hear anything. I restarted the phone, and that didn't work. I then pulled the battery, and the phone then worked normally for a while. This morning, I went to make a call and once again there was no sound on my end. I pulled the battery and it seems to be working again.
I haven't changed any settings, so not sure what to think other than to say that this never happened with 2.1, so I have to assume it has something to do with the update.