Imagine having a 3D display where lighting, viewing angles and distances from the screen were not a concern. HP's Photon technology is a 3D display that remedies all of these issues, and theoretically scales to any size screen you like.
The Photon is a thick and heavy phone. It makes no qualms about this. On the other hand, it's a fast, bright, and powerful phone. The latter's worth it—pretty rare.
Sprint's got a new jewel in their helm, and they've got decent reasons to buff it: the Photon is what Android users seem to crave these days. It's large, powerful, and, unlike its cousins, will work (securely) around the world.
From what we've heard about the development process of Windows Phone 7, rumors about the OS predated its earliest seeds. How? The secret lies deep underground in Redmond, buried with a little project called Photon.