I recently finished John Robb's Brave New War. Robb does a fine job laying out the asymmetric/4th generation warfare theme. It makes interesting reading in a number of respects, one or two of which may have been unintentional. First, Robb's discussion of Iraq is pre-surge (the book was published in 2007 and presumably written in 2006 and before), so his take on Iraq will undoubtedly be colored by one's view of the effectiveness of the surge.
On the other hand, much of what Robb says about Iraq is echoed to some degree in what Michael Yon is saying right now about Afghanistan.
On the other other hand, some of what Robb writes about is, in my view, very old wine in shiny new high-tech bottles. Although the analogies are not perfect, asymmetric warfare is not new: Bedford Forrest did a lot more damage and tied up far more Union resources chasing his forces around the landscape than he used himself. What is new is the increasing ability of non-state actors to play, but even this is not entirely new. After all, the Ujedinjenje ili Smrt (Union or Death, also known as the Black Hand) was not a state organization, and the FN 1910 pistol Gavrilo Princip used to assassinate Archduke Franz Ferdinand and Duchess Sophie of Hohnenberg sold for $64.95 in contemporary U.S. dollars.
And what did Princip accomplish with his $65 gun and two rounds? Why, the 20th Century, which saw state-organized murder on a scale to make even S.M. Stirling's Tchernobog burp and say, "No thanks, I'm driving." Pretty good return on investment...for given values of pretty good.
All that said, though, Brave New War definitely repaid the time I spent reading it, and Robb's blog is well worth perusing. He spends a lot of time discussing -- and attracts good comments further discussing -- the hollowing of the nation-state, resilient communities, and other interesting topics.