Also - less free, more lance.
I got my job at Time Out Chicago in large part because I worked for free at Chicagoist (I’d also been working in other jobs for seven post-college years so it’s not like I was new to the job market). That job led to my gig at Playboy which, despite my dislike for the way it ended and the several months preceding the end, led my current job as Director of Digital Strategy and Development for Chicago magazine.
Granted, in my job at Chicagoist I wasn’t just writing. The experience I got in hiring and managing people, editing, and event planning for an online pub made me qualified to do the job at TOC. So if the free job just allows you to get more experience writing then maybe it is a bad idea. And the original post above - from whence this text comes - from was written by a designer so maybe in that field working for free is a bad idea.
But working for free providing me with excellent exposure. So never say never. Or never say “do not,” I guess.
UPDATE: Some follow-up posts from me3dia, krisv and kiyoshimartinez are collected here.