So i bought the Tamron SP AF 90mm F/2.8 Di Macro yesterday used. I must say, this is an outstanding lens. And I was mistaken again. It is specifically built for the Nikon AF-S system and it does have a built in auto focus motor. It works brilliantly with my D40. Very easy to use, and the auto/manual focus override is quite slick! I would highly recommend this lens to anyone who doesn't want to spend the $900 for the Nikkor 105mm.
Here is a shot of the lens:
Here are a few test shots. The first one is of my Omega SMP pearl. This shot was shot at F8
This second shot of the same subject was shot at F29
Huge difference to the Depth of Field!
Here is a general shot of the top half of the dial. Obviously I should have cleaned the watch first, but I was too excited to start playing with the lens that I completely overlooked that idea!