Thanks for the compliments (although I had to ask myself whether it was a good thing to have my name written all over it ;-) ). Basically, the knife is sitting on a white sheet of paper, and is lit directly by a halogen desk lamp that doesn't have a diffuser. Intentionally underexposed by 1 stop (using f/16 to get some DOF), and then in Levels used the white eyedropper to select the background as white (it was grey due to the underexposure). Then just moved the midtone slider to get the shadow and remainder of the knife back to a normal tonal balance. There's a small curves adjustment at the bottom end, to make the metal distinct from the actual shadows.
So...the key I think is the almost point-light source, and the narrow aperture. The rest of the processing merely provides the high-key effect.
