As far as I can tell... The exchange setting is non-functional right now... but Im not sure... Its reassuring to see the setting there that maybe they will add support for exchange in the future... but look at the footnote on this tech support document from apple:
http://docs.info.apple.com/article.html?artnum=305882
or the top note on this web page:
http://docs.info.apple.com/article.html?artnum=305883