Nikon has posted an interesting (though clearly biased) interview with Hiroshi Takeuchi, one of the engineers behind the new scene recognition system in the D3 and D300. Aside from the cool graphic (above), it's interesting to read about how this has been developed (and makes me anxious to try it out).
Apparently, the tie-in with the AF system works very well, which allows you to compose your picture first, then auto-focus. This is much improved over the auto-focus in the center, then compose system that every other camera has depended on.