What's That Mysterious Metal Square On the Top of the iPhone 5?

According to rumormongers, this allegedly leaked iPhone part supposedly shows a Near Field Communication (NFC) antenna that would work with iOS 6's passbook to turn your iPhone into a digital wallet. But is it really?

According to Anandtech's Brian Klug and Anand Lal Shimpi, it's not:

Given the primarily metal backside of the new iPhone, it's highly unlikely that NFC is in the cards for this generation. In fact, given the very little space at top and bottom dedicated to those glass RF windows, you can almost entirely rule it out.

In addition to that, NFC antennas are big, thin flat inductors that work through a magnetic field. This is not it.

So what is this "heavily shielded mystery chip"? We don't have a clue. Brian and Anand think is a touch and display controller combo.

If it's real and the part is finally there in the new iPhone, we will know what the hell it does in about three weeks. [Anandtech]