Apple’s iPhone gravy train keeps rolling on, but it’s having trouble keeping up with initial demand, as shipping estimates for pre-orders the latest version have slid to 3-4 weeks, as noticed by MacRumors. When pre-orders for the iPhone 5 opened up last Friday, Apple quickly sold a record-breaking 2 million units. Within about an hour, shipping time quotes quickly jumped up to 2-3 weeks. Those estimates held steady for a few days, until they increased again on Tuesday evening (US time). Read the full story at The Next Web.