After interviewing for months I basically memorized the answers to the main kinds of technical questions. After I started to hear the same sorts of questions asked over and over, I knew the process was completely broken and I would never ask stupid technical riddle questions to gauge someone's competence on the job.

I think a brief conversation about software development and a longer conversation to determine how smart the guy is is what matters. Even someone who barely knows how to code can learn on the fly if he's smart/competent enough.