Prior to getting an iPhone 4 I used to use a iPod Touch with a GPS cradle snapped on to give it GPS capabilities. Once in a while it would lose the GPS signal, but it was rare and certainly wasn't frequent enough to annoy me. Since getting the iPhone 4 I noticed the GPS accuracy tends to fluctuate more wildly, I assume because the iPhone is doing this in real time, while the old GPS cradle I used did updates less frequently. But yesterday and today it went to absolute crap. I've been in Austin, Texas, traveled 200 miles to Dallas, and whether it was a blue sky or cloudy, this damned thing could not keep a lock it seems for more than 10 seconds before losing the GPS signal completely, then regaining it 10 seconds, later, only to lose it again, cycle, rinse, repeat. Its accuracy went anywhere from 5 meters to 1500 while I was using Navigon, causing it to go haywire and giving me directions to the frigging moon. This is the worst GPS performance I have ever seen with this iPhone, and I'm wondering if this is expected behavior due to weather conditions, or if it's a sign that the phone might be defective and needs to be swapped. Has anyone had similar experience? I noticed this happens in Google Maps too, so it's not germane to any one app. It's just more noticeable in Navigon because I depend on its accuracy there so I don't wind up driving into a river.