The Microsoft Exchange team blog (msexchangeteam.com) recently posted an absolutely phenomenal blog post that describes exactly how DPM 2007 protects Exchange Server data. With soem really good explanations and nice graphics -- we might just reprint it as a new technical whitepaper (somewhat kidding).
Our hats are off to Doug Gowans, with help from Ruud Baars and Ben Appleby. Good stuff, guys !!
If you are looking to protect Exchange Server data -- take a look at their post.
http://msexchangeteam.com/archive/2008/03/19/448477.aspx