I was going to ask this same question...glad I searched first!
There have been other discussions about heat, but I was never able to find out if "noticeably warm" is normal. While at rest (and stand-by), the phone feels cool. When charging and playing intense games, the back of the phone feels warm to the touch. Not hot, and not uncomfortable, but noticeably warm. I expect it under those conditions; as has been stated, it's really a portable computer.
But this morning, there were 9 applications that were updated in the market. So I downloaded and installed all of the updates. During the process, the back of the phone (near the camera lens) got noticeably warmer (which happens whenever I use the Internet more than briefly); again, not what I would define as "hot", but a little warmer than "casually warm" (I also understand that my hand will also warm the area when I'm holding the phone). Using the battery widget, I've never seen the temperature go over 100 degrees F.
All of this to simply ask "is this normal; does everyone experience this behavior?" I can certainly live with it, but if there's something wrong with the device, I'd rather exchange it now than wait for something to go catastrophically wrong because of the heat. Can anyone offer me peace of mind?
Thanks,
Rick