Marco.org

If “Jim is going” is a phrase, and so are “Bill runs” and “Spock groks”, then hackers generally prefer to write: “Jim is going”, “Bill runs”, and “Spock groks”. This is incorrect according to standard American usage (which would put the continuation commas and the final period inside the string quotes); however, it is counter-intuitive to hackers to mutilate literal strings with characters that don’t belong in them. Given the sorts of examples that can come up in discussions of programming, American-style quoting can even be grossly misleading. When communicating command lines or small pieces of code, extra characters can be a real pain in the neck.

— inky

I do that, too. So does John Gruber. I know the punctuation supposedly goes inside the quotes if it ends a sentence, but that’s just wrong unless the punctuation was part of the string literal I was quoting.