According to patents apparently uncovered by unwired.com, the clamshell iPhone would feature a transparent flip that doubled as a dual-sided trackpad.
The patent, filed back in September 2006, shows how the flip could have numbers and T9 symbols which appear with polarised markings.
The main benefit would be a smaller iPhone, and I love to get excited about things like this... but I remain unconvinced that this particular design will ever see the light of day.
After all, the iPhone is all about screen size - browsing the web on a half-sized display would be a real pain. Plus, it's qwerty keyboard we need, not a numeric keypad.
Perhaps this patent stems from one of the many failed iPhone prototypes mentioned by Steve Jobs in a recent interview with Fortune.com:
@Take the iPhone. We had a different enclosure design for this iPhone until way too close to the introduction to ever change it. And I came in one Monday morning, I said, 'I just don't love this. I can't convince myself to fall in love with this. And this is the most important product we've ever done.'