"Before you pop that painkiller, you might want to focus on how much better you'll feel afterwards. Positive thinking could double your pain relief."Why was anyone surprised? Tell people they are getting a powerful drug but give them a sugar pill and some people will get better as a result. This is the placebo effect, it's a real effect, it works.
So now, we find that placebo effect + real medicine is better than either real medicine or placebo effect on their own. I'm not surprised. In the world of real medicines you can get a drug-drug interaction, for example an antacid will affect the efficiency of blood thinning drugs. What would be interesting to discover a drug where the placebo effect has a negative effect on the efficiency of the real drug ... a med that only works when you don't know you are getting it. Would that surprise me? Probably not, but it would be cool to know one exists.