This is, apparently, a reasonably common phenomenon--the hot phone, if not waking up with one. Around the forums, people are blaming Push features and bad batteries, and all sorts of things. Apple doesn't seem to have responded to the complaints.
I'm starting to wonder if a recall is in the offing.
As for my experience, at first, I felt I was alone and didn't even realize I might have a problem. One does not, after all, expect to reach under one's pillow and find an iPhone that passes for a handwarmer.
Come to think of it, my iPhone has seemed warm-to-pretty-hot (compared to my old iPhone) on several occasions, The only discoloration on its black case, however, is a small skid mark where the phone hit the driveway one sad morning.
I dropped it on day three or four, when it was briefly between cases, of course. I have been very pleased with how tough the iPhone seems to be and the 3GS seems to be no exception. It still works just fine and the scratch is really more a scuff that is now covered by a rubberized case. Maybe the phone will bounce next time.
As for the overheating, I was pleased to find out that I am not alone. Other people's overheated iPhone problems are worse than mine, though I will now be paying much closer attention.
One user reported that he was recording video when the phone became very hot and died. Another--this is on the Apple Web site, in the forums--says there is a heat sensor inside that will record overheating and can be used to demand a replacement phone from the folks at the Genius Bar. We'll see about that.
The first time it happened, it resolved to make sure the phone didn't end up covered under a blanket or something and left it at that. The second time occurred during prolonged GPS use, which also seems to run down the battery fairly quickly.
I thought the overheating was odd, but didn't think too much about it until seeing our first post about the problem. I then mentioned it on Twitter and got a couple of responses from others who've also had the problem.
I am not sure what Apple can do to fix the situation. I suppose they can warn us about what causes it and how we might avoid doing whatever causes the overheating. I am sure, well, fairly sure, they will replace the discolored cases that some have reported.
It may be possible for software to fix the overheating.
Will there be an iPhone 3GS recall? Based on my experience, no. Still, battery problems are the stuff of which recalls are made and Apple has not been immune from them in the past.
Right now, my overheating issues aren't terribly serious, just surprising. As more people use more iPhones and we learn more, a different picture may emerge. A mass iPhone recall isn't likely, but it isn't impossible, either. Just see what happens if an iPhone catches fire.
David Coursey would miss his iPhone 3GS if he had to send it back. Good thing he still has his original iPhone, just in case. He tweets as techinciter and can be e-mailed from www.coursey.com/contact.