QUESTION: Which is right? "Different from" or "different than"?

Pul-eeze -- do NOT use words like "right" and "wrong" to me! Most writers freely use "different than" in order to save words. One of my guidelines is to save "different from" for use in front of prepositional phrases (you know, those preposition/object words). F'rinstance: Style manuals are different from each other.