After a gradual increase in traffic since Panda 2.5, I had a 20 percent drop in traffic from the 10th-13th. Now the interesting thing is that the keywords that I lost the majority of my traffic for were keys that I have been doing very heavy SEO for lately.
Usually I use a very diverse hypertext link building strategy - fore instance - if I am going for "blue widgets" I will build:
cool blue widgets
best blue widgets
blue widgets are awesome
But for the last month I have ONLY been building links using "blue widgets"
I wonder if part of the new Panda Tweak has to do with some sort of Over Optimization filter.
Also, several days ago I optimized many of my pages, changing the alt tags on the images, then changing the page title to reflect a similar keyword.