10-13-2009, 10:34 PM
Mono-spaced fonts without em and en-spaces should still use the double spaces after end of sentence punctuation. In other words, typewriter style fonts. Everything else should use a single space. Most wordprocessing software will put in the proper em-space. Typesetting for a book or other publication also inserts the proper em-space, but as what4 mentions, sometimes particular manuscripts should be done with two.