I'd like to respond to this from an Internet Engineer/Sysadmin standpoint...
"I'm not a programmer", so being on PerlMonks has not improved my marketability in this sense, but being here has most certainly improved my skills when it comes time to jam out low-level tools that either save a company time, resources or manpower (saving money in essence), and being able to tout my automation and consolidation skills because of my Perl programming knowledge absolutely has increased my marketability.
The people I have met here which led to the books I've purchased, countless thousands of documents I've read and practiced and problems I've tried to fix for people (most cases I'd be done long after someone else has posted but I tried it anyways) has led me to be a far greater task-manager and engineer.
The very way I look at most technical problems has evolved positively just by following the creative and insightful responses (and even questions) I've experienced on PerlMonks.
So marketability? Yes. Not because I can say I've been here or am a good programmer, but by touting what I've learned from all of the fabulous people that reside here.
In reply to Re: Is PerlMonks relevant for one's Perl marketability?