I was hit Jan 19 with about a 50% drop on my main website and like most folks, removed all the above-the-fold ads but have seen no improvement in traffic, despite everything being recrawled weeks ago. Never been hit by Panda before, actually been helped. Since Jan 19, traffic has crept up maybe 10%, typical of what happens when a Panda is run, but of course it's still barely over half of normal.
I also have a different very small low-traffic website which had Adsense ads last year, which also crept up about 10% with each Panda. Last year, I decided to remove the Adsense ads for fear Google would think it was a MFA site and it would endanger my main site's Adsense account. Within a couple days, traffic dropped 50% on the little website, for no discernable reason. It stayed that way for about 80 days, then suddenly spiked up to normal again, and has stayed normal ever since. I added Chitika ads after it got back to normal, and no change.
Now it seems beyond strange that I got an 80-90 day penalty for taking off Adsense ads on the little site, but that was the only change onsite or off, and none of the Panda runnings last year had that kind of dramatic effect, up or down. It really seemed like a timed penalty. The little site wasn't affected on Jan. 19 because it had so few ads.
So I'm keeping my fingers crossed that the above-the-fold slap on my main website contains a timed penalty also, which explains why no one has seen recovery yet, and with luck, something exciting will happen around the middle of April, or whenever the timer ends.