Rails makes up a substantial amount of queries for the bare term "Rails", even if thats an everyday word.
http://www.google.com/trends/explore#q=ruby%20on%20rails%2C%...
http://www.google.com/trends/explore#q=ruby%20on%20rails%2C%...
It's just no hype any more, but at least for half a decade. So it's also no decline.