Physicians, biochemists, nutritionists, and other researchers are starting to come around to the benefits of ancestral nutrition, and people who adopt a Paleo-like approach to eating are reporting significant improvements in their general health, body composition, and energy levels. Most importantly, there’s evidence that folks who eat this way are reducing their risks of numerous diseases and disorders that are associated with the Standard American Diet (S.A.D.).
The NY Times had a blog article on Good News on Saturated Fat which is reporting on Gary Taubes's interpretation of the new report in The New England Journal of Medicine on a two-year diet experiment in Israel. A followup is the post The Fat Fight Goes On where Gary rebuts the arguments against the study. And here's a good interview with Taubes (and includes a good summary): Gary Taubes on Cold Fusion, Good Nutrition and What Makes Bad (and Good) Science.
One larger randomized controlled trial followed 70 post-menopausal Swedish women with obesity for two years, who were placed on either a Paleo diet or a Nordic Nutrition Recommendations (NNR) diet.  The Paleo diet provided 30% of total calories from protein, 40% fat (from mostly monounsaturated and polyunsaturated fats) and 30% carbohydrates. It included lean meats, fish, eggs, vegetables, fruits, berries, nuts, avocado, and olive oil. The NNR diet provided less protein and fat but more carbohydrate with 15% protein, 25-30% fat, and 55-60% carbohydrates, including foods similar to the Paleo diet but also low-fat dairy products and high-fiber grains. Both groups significantly decreased fat mass and weight circumference at 6 and 24 months, with the Paleo diet producing greater fat loss at 6 months but not at 24 months. Triglyceride levels decreased more significantly with the Paleo diet at 6 and 24 months than the NNR diet.