...is a phenomenom written about (in several different contexts) by Paul Miller.
Basically, this points out that in a number of fields (astronomy and open source software being 2 examples), progress is now being made by groups of dedicated amateurs working to professional standards, rather than exclusively by professionals and academics.
Paul Miller's thinking goes beyond this - he has written a numnber of interesting papers for Demos.
One Pro-Am example that springs to mind which I am involved in is the experimental aviation community, where many planes are built to better-than-professional standards, and where Burt Rutan (heard of him?) started out designing planes for that community before (as he put it recently) "we all grew up and got day jobs".