I was going to write a proper blog post, giving in to the recent influx of demands from my audience of three (well, I know of at least three vocal members -- who knows how many more are lurking in the silent faceless mass?).
Then I came across this NHS-sponsored video of doctor and Grauniad columnist extraordinaire Ben Goldacre, MD, explaining the wonders and implications of the placebo effect. There's nothing I could say that could top it in terms of clarity and public interest, so I'll bow out for now and leave the stage to my betters. Ben, take it away.