I've noindexed about a dozen pages on my site, but I am wondering in retrospect if I made matters worse.
My site has several hundred thousand pages. I noindexed about 1300 of the ones that were hit hardest by Panda (overall 60% traffic loss between Panda 1.0 and 3.6). We seem to have gained about 10-15% of that traffic back since Panda 3.7, but I have no idea if it was the noindexing that finally made the difference (it was done between Panda 3.6 and 3.7). I'm not going to believe that any one thing actually works until we've remained stable (or continue to regain traffic) through a couple more updates.