Personally, I listen to people who have made money in the field I'm in, which is programming and specifically web applications. To that end, I tend to listen to people like Paul Graham and Joel Spolsky. Both of them feel that you have to justify using a non-dynamic language because it costs more to do so.

I've gotten jobs through Dice. Every single one was a contracting firm that would literally cut'n'paste the customer's req into the Dice form. Often, I'd see 5 companies advertising the same position¹. Do those count as 5 jobs or one?

Another way to look at it is the number of Fortune 500 companies who would go out of business in a month if their Perl programs stopped working, then compare it to the number of Fortune 500 companies who would go out of business in a month if their XYZ programs stopped working. Seeing as I know of 4 Fortune 500 companies where I've personally worked that would keel over if all their Perl or COBOL programs stopped working, but nothing else ... you do the math.

1. This is actually a problem because you can get into image problems if you accidentally get submitted to the same job by more than one company, especially if you sent your resume in at 3am to 200 postings like I used to do.