Yep. I've seen the failsafe warning come out a couple of times. That was before 2.2 though when the "performance" was the governor it automatically set for some reason. I use ondemand now though. Haven't had a failsafe warning with this governor yet. Maybe if I'm outdoors in the heat, but haven't yet.
Using the phone in the car as a gps I did discover the battery going lower and lower. The phone wasn't charging. I forget the temp now, I think it was 120F, but the phone doesn't charge above a certain temp. It probably knows that charging will add even more heat to the mix. I took it off the car mount and held it in front of the AC until it cooled down below 100F. I left it in the center console for the rest of that trip, out of the sun.
Wow. Actually, when I had my iPhone the GPS would make the phone hot as hell. Ever since then I've always had a habit of using the GPS, but only opening the app when I feel like I need to look at it again, just to avoid that heating issue too. I remember leaving the GPS run a whole trip and the phone was just too hot to pick up
The dash is black, the phone is black, the sun was shining, it was hot outside. AC was on vents, not on defrost. Even trying defrost didn't help as the air headed up the windshield and missed where the phone was mounted.