Apple is signing up a second major manufacturer to produce the fourth-generation iPhone, industry sources claim. Pegatron Technology, an ASUS subsidiary, will allegedly fill in alongside Foxconn, a long-time Apple partner already manufacturing the iPhone 3GS. Though Pegatron has refused to comment one way or another, it has said that its phone shipments should grow significantly during 2010. The company has also landed several other phone contracts, the sources say.