Review of a timely and scary book (good read, scary topic); see Karen's post for more details
Politics aside, "Where Have All the EMails Gone?" is an good case study of what not to do if you want to keep e-mail secure, auditable, and recoverable. The book is an easy read and is peppered with repeated disclaimers of political bias by proving that this problem is non-partisan having started in a Democratic White House and has come to our attention in a Republican White House.
Check out the companion web site and think about reading the book -- it's a useful survey of some important email market dynamics, and also an objective (and mostly nonpartisan) assessment of what appears to be incredibly bad IT policy within the White House.
A quote from p. 176:
If you take away anything at all from this book, please make it this -- email in the White House needs to be fixed. Not because we want to give Congress a bigger stick with which to beat on Presidents, but because some really bad things could happen if it's not fixed.
Migration from Notes/Domino to Outlook/Exchange in the midst of a war, Karl Rove's habit of losing Blackberry devices, and much more -- quite a story.