This is a bit off the wall. I went skiing yesterday and had my phone (t-mobile G2x) in an outer pocket of my parka. The air temperature was about 25F. When trying to unlock the phone all I got was a blank screen and an unresponsive power button. Rebooting the unit by removing the battery yielded the same result.
The phone is fine now. I do not see any operating temperature information listed in the specifications.
I assume there is a recommended temperature range because I have had these things overheat and crash on me. Just like my computer
*which I accomplished without dropping anything while on the chairlift.