I noticed a few of you might be curious to learn this so I thought I'd post a quick how to!
****This was made with the assumption that you know your way around photoshop at least a little bit.
--Open the scanned file. (Make sure its black and white!)
--Go to the Channel Palette (should be the tab next to the Layer Palette).
--Click on the icon that looks like a blip at the bottom.
--Invert the image either while it is selected, or not (ctrl I) - it should become black with the drawing in white
--Go back to the layers palette, make a new one.
-- Delete the original drawing, you should have just the line drawing left, lock it with the checker board button at the top of the layers palette. Deselect everything if you haven't yet.
--Create another new layer and move it below and fill it with white so you can see the line work.
--Select the line work layer and color away!
Hope this helps! Let me know if you have any questions