What's new about Scott McClelland's new tell-all book? Nothing, except that this book was written by a former Bush loyalist. And even this isn't all that new: there's been Paul O'Neil, Richard Clarke, George Tenet, etc; all of whom held non-trivial positions within the administration even though they were not as close as McClelland was to Bush.
A brief look at the book's chapter headings suggests that the content of the book is probably going to be nothing new:
The Permanent Campaign
Triumph and Illusion
Revelation and Humiliation
Out of Touch
We are officially in an era in which the obvious can still be controversial. The war in Iraq was sold with misleading reasons? Duh. Any one of these chapter headings could have been picked by a "liberal" blogger on the Daily Kos or a columnist on the New York Times. So What Happened is going to be less important for its content than its author. The debate is already centered on McClelland's credibility ("betrayal") because we've already heard its content regurgitated umpteen times by the "liberal media."
When it comes to White House exposes, anyone from the inside has an ax to grind (or some books to sell) and everyone on the outside is just ideologically biased. (Indeed, we needed a dog and pony show only to demonstrate that Scooter Libby had obstructed justice when almost everyone believed that he was instrumental to the outing of Valerie Plane's identity.)
So the media's hoopla and the hullabaloo will get us nowhere. We will never ascertain the truth (even if we correctly intuit it) because in our hyper-partisan era everything, even the obvious can be turned into unverifiable opinion. And as the media and pundits spend their time churning over motives, credibility, and the nitty gritty maneuvers of plausible deniability, the culprits in the White House will get off scot-free. Now that's a coup - the greatest accomplishment of the Bush administration is that it has succeeded in making the obvious debatable.