Has Ruby on Rails become mainstream? Cedric says "no", TIOBE and Tim both seem to suggest yes.

For my part, I don't care. As a polyglot programmer, I find the language wars to be too coarse-grained. I am more interested in which ideas became mainstream. As a speaker at numerous Java and Ruby events, I get a chance to see what thousands of other developers are thinking about. 2007 was a great year--a lot of ideas that have bubbled slowly for a while finally came to a boil:

Ideas that went mainstream in 2007

• Functions as first class objects. "Dude, not everything is an object."
• Closures. Is there anything they can't do?
• 100% test coverage. Untested code is legacy code, even if I wrote it yesterday. And remember, "red lines provide the real value."
• Open classes. The Move Method refactoring works a lot better when you are actually allowed to do it.
• Polyglot programming. As Steve Yegge says, "an 'X programmer', for any value of X, is a weak player."

BTW, Relevance is hiring senior developers. We're more interested in your ideas than in your language of choice.