My main site (UK market) got hit around October 11th with a 70% reduction in Google traffic. The only update around that date was the "too many ads above the fold" update. I do not have Adwords or anything like that but I did have in a few pages some ads above the fold which I obviously removed. However many of my competitors in my niche have far worse. I find that several pages have been hit much harder than others, and that there seems to be some sort of traffic shaping, because I used to get a big peak in the evening, and now I find that if one hour there is a steady flow of visitors, the next hour or two there is nothing, and so on. Also UK traffic has been the main affected, as it still gets traffic from other countries, only that this doesn't convert.
This site had been a bit unstable in the last 2 years where Panda was concerned and it was hit several times, only to recover fully after a few weeks with the next update each time. I found it a bit strange but the hits never stuck so it wasn't so bad.
However it has now been more than a month since the last hit and there are no signs of recovery. Were many sites hit by this update, any indication of how they recover?