A microwave over the range will probably be listed as an exhaust fan. If it is, and it is cord and plug connected, it requires a dedicated circuit per 422.16(B)(4).
Sorry, I should add that this would not apply to a typical, counter top type of microwave. I didn't see it specified one way or the other in teh original question, and that is why I threw it out there.
[This message has been edited by Ryan_J (edited 11-20-2006).]
