My Rule: The nature of a negative (i.e. final) communications should equal how personal the relationship is. If you applied electronically and we stated "only those considered will be contacted" or you cold-emailed me some sales pitch, we don't have a relationship at all and you deserve nothing. If you contacted me and I responded with a short email, my final answer should be a shjort email. If you spent several hours in face-to-face interviews and we're not moving forward I owe you a phone call or email with some explanation of why - in a TIMELY manner.

Seems pretty easy to me.