I like this guide to interviewing candidates: Joel Spolsky's The Guerrilla Guide to Interviewing. It's definitely not Perl-centric, but it's a good guide for technical interviewing.

In general I definitely agree with the fact that you need to get a sense of how good a programmer your interviewee is. And you can't do this by asking trivia questions; I think you really need to see code samples, and you need to get the interviewee to describe how they go about solving problems.