And the answer is...
The dots are part of the Space Vision System. The location of each dot is carefully mapped in a computer database, allowing the operator of the Remote Manipulator to precisely position objects - or the arm itself with respect to an object - without having the target in clear line of sight. As the size of ISS grows this will become more of an issue.
I've heard that it currently doesn't work very well.
-Kim-
Pad Rat, KSC
http://www.geocities.com/kimekeller