http://www.wired.com/medtech/drugs/magazine/17-09/ff_placebo_effect?currentPage=1
Far too long to reprint here. Article discusses the fact that placebo reactions in drug trials have doubled over 20 years, while the drug reactions have dropped. Discusses some actual physiological reasons for the placebo effect, brings up some interesting limitations to it, and argues if the testing is increasingly flawed, creating an increased placebo response, or if it's real.
This was very well written, especially for Wired. Both sides of each arguement seem to be given equal credence.