While you are at it look at JavaScript and Node (or at least node.js).

Having serious exposure to multiple languages increases the number and variety of gigs you can tackle. It puts you in the position of letting the Problem Domain determine the Language -- time sensitive jobs in C; text handling in in Perl or Python; regular expressions in Perl; web-code in Perl, PHP, or AJAX (or node.js and the web-server of your choice). Increased flexibility reads as increased marketability.

In addition to increasing the chances of getting hired/assigned to interesting projects, there are cross-pollination effects -- the way that I look at designing a Perl code effects the way I look at writing Python tools for Ops Monitoring folk. Thinking about how Perl's CGI module works influences the code that I write in JavaScript (and conversely). You don't need to be a Super Star in the language, but you do need to be able to truthfully say (and demonstrate) that you are a Journeyman Programmer in whatever language the project needs.

While you are at it, don't restrict yourself to learning one or two other languages. I am currently working my way through node.js and JavaScript (again, after I read Doug Cockcroft's little book). When I have reached my comfort level there, it's time to go back to FORTRAN; my third kid is working on some interesting problems involving mapping software for the Forestry Service. All of the code is written in either FORTRAN or Python, and there are some interesting issues and problems there. (Think real-time maps of forest fires....)