TIOBE Software has released its programming community index for December 2011, and the numbers show that C# is gaining in popularity.
According to TIOBE, the most popular languages right now are Java, C, C++, C# and Objective-C. (In that order.) There's no movement at all in the top 3, though TIOBE says that C++ has lost a bit of popularity since December 2010. C# moved up from 5th place to 4th, and is just a hair behind C++.
The TIOBE Index from the TIOBE Software Site
The TIOBE ratings are based on the number of page hits for languages by searching for "languagename programming" in Google, Wikipedia, Blogger, Bing, Baidu, YouTube and Yahoo. The full description of the ranking algorithm are on the TIOBE Programming Community Index Definition page.
Alternatives to TIOBE
Though TIOBE is frequently cited, it's been criticized and there are a number of alternatives that are worth looking at as well.
For example, the Transparent Language Popularity Index, which is an open source project that anyone can examine and run on their own. According to the most recent query from December 1st, the top five are: