hi.
rummaging in google labs I found google trends. quite cool stats you can get there about ppl looking for a specific term.
about blender:
http://www.google.com/trends?q=blender&ctab=0&geo=all&date=all
*note: this is only about ppl looking for the word “blender”. does not exactly mean the program, but for example the 2.4 release is noticeable.
enjoy