Sharpening now has 4 sliders in CS3 for really quick and selective use. The sliders are Amount, Radius, Detail and Masking.
Set your photo to 100% or more, this trick won't work unless you set it to at least 100%.
Now, hold down the alt key and move the mask slider so that you do a selective sharpening. Choose what you want to mask and what you want to sharpen. You'll be able to see exactly what will be sharpened and what will be masked.
This is just the beginning. Do the same thing with the other sliders to fine tune. If you need to do sharpening, this is terrific and a big time saver. Best of all, your really able to target what you want done.
Hope this is helpful, Dave