While Apple’s 1st generation iPhones won’t ship until next month, the company appears to be making plans for a 2nd generation of iPhones that will ship sometime in September.

Quanta, which already builds iPods and MacBooks for Apple, commented today on reports that it will be building the updated iPhones:

Quanta and Apple are building a tighter than ever relationships. Quanta not only manufactures NB and iPod for Apple, but also may have received the order to make the second generation of the Apple iPhone. iPhone is a smartphone based mobile, and the second generation model shipment is expected in September 2007 with forecast of 5 million units in 2008.

While neither Apple nor Quanta is commenting on the next-gen iPhones, there is speculation that the new iPhones either be for European markets, or will have larger Flash memory capacity.