Dr. Michael Eades has posted an absolutely spectacular commentary on the Paleolithic diet concept:
Rapid health improvements with a Paleolithic diet
The post was prompted by publication of a study that tried to recreate a Paleolithic-like diet experience over a brief study period:
Metabolic and physiologic improvements from consuming a paleolithic, hunter-gatherer type diet.
Dr. Eades discussion is wonderfully insightful and comprehensive and there's little to say to improve on his discussion.
I'd make one small point: From what I see in my experience, the improvements in lipid patterns seen in the brief period of this study are very likely to have been primarily due to the removal of wheat . Followers of this blog know that wheat elimination is among the most powerful cholesterol-reducing strategies available.