Check out this interesting article on the effects of acupuncture on patient satisfaction and health and decide for yourself whether or not this is a practice that actually works.
Researchers looked at a huge (>10,000) pool of patients who had undergone acupuncture therapy with the goal of determining whether or not more experienced clinicians were more effective at performing successful acupuncture treatments.
I'd say that there is a large body of evidence to suggest that acupuncture has a significant positive effect on people with numerous health problems, but that would be a bit misleading. What we actually have is a large body of anecdotal and poorly-controlled knowledge that we've been using as justification for sticking needles into people for hundreds of years.
Naturally, the researchers found that there weren't any differences in outcome between experienced acupuncturers (?) and freshly-minted newbies straight out of school. What they did find, however, was that patients did report a significant increase in effectiveness if they had preconceived beliefs in acupuncture or felt strongly that eastern medicine was a viable practice to treat sick people.
What does all of this tell us? Unfortunately, I can't help but see a big fat "placebo effect" going on here, but does that mean we should shun acupuncture and all of its fancy shmancy eastern medicine cousins? I think not.
Whether or not these practices have a physical effect in the body, they do have an effect on the mind, and while putting needles in your skin may not stop your back pain, it may convince your brain to stop telling you that you've got back pain.
Ultimately, our reality is constructed by our brains. The real world is only real inasmuch as the mind has painted it that way. Even if this acupuncture stuff doesn't actually do anything to our bodies, it manages to trick our minds pretty well. Who can say what the difference is, really?