Or are perl developers just slowly drying up and as such in very high demand?

I suspect it's a case of high demand and thinning ranks, coupled with the ranks not being replenished with fresh blood.

Many of the people I work with who are a few years out of school learned Java in school, and have been cramming on Ruby and JavaScript so that they can do fun stuff. Rails has proven to be a very potent gateway drug for Ruby, and Ruby can do most of what people often use Perl for. Not as well in some cases, but well enough. It's helping set a higher bar for Perl6.