The tipster was able to get a very good look at the device but unable to snap a picture to "do it justice". After returning home and seeing the green cases photos posted online yesterday he determined that it was likely a legitimate device.
"Almost EVO-like" in screen size, this iPhone also appears thinner than the current iPhone 4 but also wider. The edges are rounded metal like the edges of a Samsung Galaxy Tab 10.1 but could still function as an antenna. The back is a curved/tapered glass or plastic. He couldn't tell but if he had to guess he'd say glass. He said it looked too amazing to be built by anyone besides Apple (fanboy!).
The man using the device was apparently making an effort to hide what he had. Apple does do real world testing of their upcoming devices as the iPhone 4 leak is evidence of.
Take a look at the photo and let us know your thoughts!