there's many language popularity ranking sites. The most well-known, is tiobe.
I think TIOBE index is stupid. Their approach is not good. Mostly because, they tried to be general, as if they know what “popularity” means.
another one, http://langpop.com/, is worse. And badly maintained.
the following is better, because they are specific on what they measure.
note: language popularity is a lose concept. Is it more talked about? is it more used? more used by companies or by loud amature programers? Is it more existing code? How do you count code? What about quality code, but are not public?