punctuation - Is it ever acceptable for a period to come after a quote at the end of a sentence?

I've heard that you should always place ending punctuation inside of quotes, no matter what.

Are there any cases where it is appropriate for a sentence to end with ".?

Answer

Yes. See the Economist style guide:

If the quotation does not include any
punctuation, the closing inverted
commas should precede any punctuation
marks that the sentence requires.

More at the Guardian style guide.