iPhone HD may have been seen in complete form today through a discovery in San Jose. Lost by its owner and hidden in an iPhone 3G case, the device would be a radical redesign that should include the front video camera that justifies the taller build. It would also have 80GB of maximum storage rather than the more likely 64GB, according to Engadget, and was running a newer version of iPhone OS (likely 4.0) before it stopped booting.
Cosmetically, the phone would be the first major re-imagining since the iPhone 3G and would have aluminum sides, not unlike the iPad, but with buttons for volume in place of the rocker switch. It appears to have a flatter back that's still made of plastic to maintain the necessary cellular reception. The model appears to be a prototype as it uses "X" as a placeholder for both the capacity and identifiers like the FCC ID.
Assuming the device is real, it remains possible that the iPhone shown won't be directly reflective of the final model as Apple is known to make design changes even very late into development. However, Apple usually needs to start mass production of iPhones in spring ahead of an early summer launch and thus may have had to produce a small batch for testing.