I went through the first five pages (200 posts) of the famous Google Forum thread "Think you're affected by the recent algorithm?". I found 31 sites that were actually hit by Panda (used Alexa), most of the full recoverys were in September, others recovered temporarily then crashed again. It was a very strange tour.
The number in parenthesis is the current Alexa US rank.
#1 (2588) recovered late September
#2 (10,948) recoverd mid May, fell again late June
#3 (26,451) down and flat
#4 (38,329) down and flat
#5 (56,683) down and flat
#6 (6,884) roller coaster, and jagged
#7 (10,813) up and down, full recovery September
#8 (13,688) down 2010, down Panda, some recovery September
#9 (61,027) down, summer recovery, down worse
#10 (37,401) way down, way up, down (IN rank)
#11 (77,601) down and bumpy, was falling since mid-2010
#12 (9678) down and stayed down
#13 (18,697) down and flat (big 2010 run-up)
#14 (1882) down and still drooping (down since 2010 peak)
#15 (93,976) down, up, flat, not 100% it's Panda
#16 (4809) down, down, big July recovery, par
#17 (755) down, down, drooping
#18 (22,913) down, down, spiky
#19 (46,275) down, down, down
#20 (4,367) down, up, down, flat
#21 (25,842) down, down, drooping
#22 (54,886) down, drooping
#23 (47,232) down, down, flat
#24 (2,439) minor Panda hit and flat after big fall earlier
#25 (34,449) down, down, flat (with seasonal spikes)
#26 (12,817) down, way up, way-way down, flat
#27 (28,013) down, drooping
#28 (54,128) down, down, drooping
#29 (25,21) down, trend up, full recovery late June
#30 (56,389) down, down, flat
#31 (31,800) down, down, flat to 2010 baseline
So there were only four full recoverys in the bunch so far, but that beats none. It seems to me that penalized sites were in a small number of subject groups, but they are self-selected reporters to the Google thread. I'll look for reasons as I have time in coming days.
Writing it up with subject area and site descriptions, maybe some webmaster interviews, would make great link bait for somebody who wants SEO traffic. Yuk!
[edited by: tedster at 7:53 am (utc) on Nov 22, 2011]