a Google-based ranking of languages based on job openings, books, and training courses

That's a tad euphemistic. I always knew management is more based on hearsay than science ;-). Now I know why:

Q: How are the TPCI ratings calculated?

A: The Google search query doGoogleSearch('+"<language> programming" -tv')/10000 is used to calculate the TPC Index. This very simple algorithm appears to work quite well in practice. In order to professionalize the index further, there are thoughts to enhance the applied formula.

(Source: the URL you cited)

Let's put "PerlMonks -- the perl programming community" on every single page in the perlmonks mirror for google, and we should be able to make #1 easily :)

(Actually, I think we should really do it.)