There are sites that come out of Panda, we just did. We were hit with Panda 2.2. On June 17 at 1800 (eastern time), Analytics showed me a clear drop off in traffic of 45 to 55%. It was all Google. Very obvious. Over the coming weeks, this was evident in GWT, where I could see ranking decreases of 3 to 10+ positions on thousands of keyphrases.
On July 12, at nearly the same time, Analytics showed me a very clear increase in traffic of 120 to 130%. Again, this is very obvious because it's a mid sized site that went from 545 visitors to 1,253 (week over week - actual data for the hour 21:00 last night).
Nothing else happened in this timeframe, we have about 1,300 pages in Google's index, and that number was very steady over the last four week.
Again, when you go from 25,000 visitors a day to 11,000 you know something happend.
That trend continues this morning, back to pre 2.2 levels (perhaps doing slightly better, way too early to tell).