I ran into this very cool site called TIOBE software. (TIOBE stands for The Importance of Being Earnest.)
They have info that I've wanted to know for a long time - Technology (language) trends. It's not perfect, but you have to start somewhere, and it's pretty well done.
The index is supposedly developed from the number of engineers with certain skills.
Interestingly the top languages are Java, C, and C++. Even more interestingly, ActionScript just entered the top 20.
More info at the TIOBE.com site.