Not, I think, peer-reviewed science this time, but two articles from Nature and Science respectively, both on the subject of sports doping, a subjetc which is of course very topical given the Beijing Olympics, due to start tomorrow, 8th August. The first is a Commentary article from Donald Barry on the statistical significance of doping tests, focussing on the case of Floy Landis, who was stripped of his 2006 Tour de France victory following a positive test for testosterone. The second article is one of a series of News articles in Science related to the upcoming Olympics, and questions whether performance enhancing drugs really do benefit performance.
The figure on the left is included in the article - it shows delta notation of isotope ratios of 167 samples tested at the LNDD (who tested the 2006 TdF samples, including Landis'), those considered positive are in red, those negative are in green. I don't think these samples are necessarily derived from the Tour, if any, since a good number are considered positive.