There's been prior evidence—and this might be more: a leaked screen protector and possibly-revealing case.
BGR spied the leaked case accessory, which briefly made an appearance on Case-Mate before they yanked it down. Oh, and is that an aluminum back I spy? I hope so.
In addition to the case, an allegedly-real iPhone 5 screen protector appeared in the wild. Unearthed by Hong Kong tech site Unwired.hk, the screen film also backs up the expectedly-widened home button. The dimensional difference looks to be the same illustrated by the leaked case from earlier in the month. We'll find out for sure soon! Very, very soon.