That's an interesting way of looking at it. I've interviewed plenty of candidates in the past, and if someone I was interviewing asked me a whiteboard question when I asked 'do you have any questions for me?', I'd be amused, pleasantly surprised, and impressed.

And I'd probably be more likely to want to hire them, too! Asking their interviewer a technical question would show me that the candidate cares about the quality of his or her future co-workers.