No really. I was hired in my current job 3 years ago, with experience. I didn't know Django, but had read enough, and seen a talk on it by someone else. I learned Django on the job, but my previous knowledge of databases and Perl complemented that. I didn't know Python, but its similar enough to Perl, I just googled to find the Python equivalent. Once you have a seen a couple of languages and concepts, learning new ones doesn't always hinder you so much.
