How many Perl jobs are turning into Cobol-esque jobs. Maintain a legacy systems and keep it chugging along. How many people build new projects in Perl?

Agreed. Each metric has it flaws. Two differently biased metrics are better than one.

Removing Java and C from your list makes it much easier to see what's going on: http://www.indeed.com/jobtrends?q=python%2C+perl%2C+ruby%2C+...

Right. Now view the same stats in Relative (which makes the trending more visible):

http://www.indeed.com/jobtrends?q=python,+perl,+ruby,+php...

The numbers say what most people know: that set of four languages contains 1 that is mature and 3 that are growing. One of them is growing fairly rapidly relative to where it was when the data set started out.

You wouldn't consider PHP mature?

Or Python, for that matter... I mean, it's 17 years old. It can drive a car and almost vote!

Yeah, the post is based on TIOBE stats. LangPop.com is way better:-) Well, honestly it's still far from perfect, but there's just no way to get really good, clean data for programming language usage throughout the world.