The overheating appears to affect the white model of the iPhone more, causing the plastic cover to turn pink or brown. The problem occurs while using applications that use the iPhone's GPS and 3G wireless components.
"I have a black 32GB 3GS and recently I experienced overheating when I was using GPS," an Apple customer reported on Apple's discussion forum. "Every time I use GPS it somehow overheats, however mild it may be. But in a region where 3G is out of reach and the phone switches to Edge (an AT&T wireless network), the overheating is unbearable. You must shut down the phone."
No word from Apple on the problem, but smartphone heat has been a problem before. Japanese Wireless carrier NTT DoCoMo, for example, had to pull Research In Motion's Blackberry Bold from store shelves because of overheating problems.
The iPhone's overheating problem was first reported by the French tech site Nowhere Else.
Meanwhile, users of the iPhone OS version 3.0 report that application icons sometimes disappear or end up linking to the wrong applications. The bug was previously reported in the beta version of the software, according to the site iPhone FAQ.
iPhone OS 3.0 ships with the iPhone 3GS and is available for download for the iPhone 3G and iPod Touch.
Fixes reported by users include reinstalling the applications via iTunes or resetting the iPhone.
InformationWeek has published an in-depth report on smartphone security. Download the report here (registration required).