I was recently looking at the specs for the Fui FinePix S6500 fd, a tempting advanced amateur camera that sports 6.3 megapixels, 28mm-300mm lens, Raw file capability, and face detection technology. In fact, that's what the "fd" stands for in its name.
Face detection was certainly the buzzword at the recent PMA show in Las Vegas. Fuji, Canon, Nikon, Pentax, and Samsung all had cameras available that could automatically identify faces in a composition, then adjust focus and exposure for them. No more misfocused shots. No more overexposed flash portraits.
I dug around a bit and found a pretty good article by Jason Schneider titled, Does Face Detection Technology Really Work?. In the piece, he walks you through the theory and practice of this latest hot feature, and comes to the conclusion that yes, it indeed works.
Is face detection a feature that we absolutely need right now? Not necessarily. But odds are good that it will be available next time you go camera shopping. And it is useful when you're shooting candids and don't have time use the "lock focus and recompose" technique.
Face detection probably isn't the breakthrough technology that image stabilization is, but it's darn handy and will probably save thousands of candids all across the land.