Supplying the cases is AVY Precision Technology, and both TPK Solutions and Wintek Corp are supplying the touch screen panels. All companies are based out of Taiwan.
TPK, through its German counterpart, Balda, was the initial supplier for the iPhone touch screen module. It's unknown whether Balda is currently involved or whether Apple went directly to TPK.
The flow of information through Apple's suppliers has always been sparse, due to Apple's stranglehold on its own product message. Competition in the Taiwanese electronic component industry is fierce, keeping individual manufacturers toeing the line with Apple. But now that components are actually shipping, it's harder to hide how things are shaping up for the as-yet-unannounced product.