Apple has posted a special iPhone 3GS and 3G temperature warning on its official support pages.
The Apple iPhone support page, "Keeping iPhone 3G and iPhone 3GS within acceptable operating temperatures", states:
"Operate iPhone 3G and iPhone 3GS in a place where the temperature is between 0º and 35º C (32º to 95º F).
"Low- or high-temperature conditions might temporarily shorten battery life or cause the device to temporarily stop working properly.
"Store iPhone 3G and iPhone 3GS in a place where the temperature is between -20º and 45º C (-4º to 113º F).
"Don't leave the device in your car, because temperatures in parked cars can exceed this range.
If the interior temperature of the device exceeds normal operating temperatures, you may experience the following as it attempts to regulate its temperature:
- The device stops charging
- Display dims
- Weak cellular signal
- Temperature warning screen appears with the message "iPhone needs to cool down before you can use it" (see image above)"
Apple's support document gives some credence to these reports, although whether it's an iPhone problem or general smartphone/portable device issue remains to be seen.