I am pretty sure that iPhone 5 will not look like that. Apple is not going back to iPhone 3 round corners.
What about iPad 2 rounded corners? iPod touch 4G rounded corners? Or MacBook Air rounded corners?
Rounded corners make the device so much nicer to hold - I think the iPhone 4 is actually a bit of an anomaly with its sharp, hard edges. I would be surprised if the iPhone line doesn't go back to a rounded-corner design at some point.
, I tried.