PS 7 also has it. To use it to find those horrible dust spots do the following :

1) open original image
2) create duplicate layer
3) select duplicate layer then ‘equalise’ (from tools menu)
4) select original layer
5) selecte healing brush icon (3 squares on a diagonal) and apply to dust spots.
6) Turn off / on layers to make sure all are gone
7) Delete the duplicate layer (not the background layer)

voila – a dust free image.