Google trends is a nice idea, and I had to apply it adhoc to Java, Ruby, Python and C#. Interesting results, I can see a decline in Java! We're doomed :-)
And the Rails evangelists jump in and present this. Probably people would search for that or even that because Rails mostly doesn't find RoR though. All others ignore the quabble and use Jetty or Grails.
For fun try this.