There is a nice datasheet about DPM 2007 for Exchange in the DPM’s website.
You can check it out at http://download.microsoft.com/download/0/9/6/09623531-cb39-475a-88b7-1de963a99d9a/DPMv2_Datasheet-Protecting_Exchange_Server.pdf
Technorati : DPM 2007, Exchange 2007