Here is Wiens' response to an email from MacTrast about the button.
It looks like the home button will still have a physical clicking action to it still like the 4, 4S and 5. The additional square section next the the button is something new and probably suggests a fingerprint sensor given all the rumor wire chatter on how Apple is expected to add that feature. It looks like that part of the cable flips over the button and sits between the clicking action and the plastic button cover.
So I’d say yes, these photos, if legitimate, corroborate the fingerprint rumors
As you likely know, Apple is expected to unveil the iPhone 5S and iPhone 5C on September 10th.