Does Glucosamine/Chondroitin work for you?

Over the years I've developed some mild joint pain, particularly in my knees.  It's probably the result of my body type and build, many many years of long distance running, and just plain getting old (I'm 45).  I've been taking glucosamine/chondroitin for over a year now and have noticed improvement.  But here's the thing:  Is the improvement from the supplement, or from better training, other supplements, yoga and Pilates classes?
 
Is there good independent research backing up the claims glucosamine/chondroitin works?  Have you guys had success with it?  The stuff is not cheap, and if it's just a giant placebo, is my money better spent elsewhere?

I have noticed a  decrease in joint pain after taking glucosamine and chondroitin. I started on it after a friend suggested it and it worked wonders for me and him. I am sure yoga and pilates have helped also but my personal opinion is that it is worth the money.

Sivic02,
    Thanks!  I'll keep taking it!

I think it works, and can be fairly cheap when Costco puts it on sale.  It does however take a while to start working, so you either need to be on it all the time or don't bother.

OH,
   Thanks!.  I get it at Costco w/coupon.

I've been taking it for a couple months, and it seems to help a lot.  
But if you're skeptical, just stop taking it for a while and see how you feel.