Merit pay for teachers

I just read the postings following a editorial piece about teacher pay.  Here in Utah, teaching is seen as a calling--particularly for those who can't make it in the business world, or those who are lazy and don't want a real full-time job.  Both notions are laughable.

Teaching is an amazingly difficult profession, full of frustration and annoyance, powerlessness and masochism.  Yet it can be immensely rewarding.  What other profession would have some young adult calling your name in a mall, or coming up to visit in a department store?  An appreciative hug from a 21-year-old that was in your class when he was 12 is a powerful reward.

Merit pay is such a slippery slope.  It pits teachers against each other rather than encouraging cooperation and support, and support is absolutely necessary for new teachers.  Merit is also difficult to measure.  Do principals make those decisions?  Parents? Students? Other teachers? Whose opinions are most valued?  Why?  It's way too sticky for quick decisions.