Different from/than/to

Growing up in Melbourne, Australia, I was taught that the correct preposition to follow the word "different" in a comparative sentence is "from", as in "John is different from me" (which I believe is also the standard in the UK). I think in some contexts "different to" was considered acceptable, but "different than", which I often see in US publications, was not.

I've wondered about this for years. Whereabouts is "different than" considered correct usage? If I were writing something for a US publication, would my editor change "different from" to "different than"?