I am in agreement with John on this one, for the most part, how ever an apostrophe can be used to show possession if the name ends with an s for example "Frances' book" although really the apostrophe is still indicating a missing character, an extra s.
Edit: a Google search just turned up this:http://en.wikipedia.org/wiki/Apostrophe Apparently both possession and representing missing characters are correct usages.
edit again: we seem to be cross posting
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