One of the things that is not so obvious about this fellow's work is that much (if not most) of his photorealistic art is not only
not done with photo references, but can't be done with photo references. He does quite a lot of high tech artwork for the military and if you look at some of that work, you'll see that he hasn't copied any pictures. That's where photorealism becomes an art. When it is used not to copy a photo, but to produce a photo "quality" image that could not (or at least not easily) be taken with a camera.
For an example, take a look at this one:
Timing is Everything
Having said all that, I'm not a huge fan of PR style, but this guy is really amazing. Great thread!