It's a rollercoaster.
I posted earlier about my sites being affected by Panda2.1.
Suddenly yesterday total traffic and adsense up to the level of a pre-panda 2.1 above average day. Whoo-hoo I thought. Looked at SERPS and little had changed (one or two sites had crept back up a little but not much). Careful analysis showed it was just one site (my main site)that was getting more traffic, but SERPS were still the same (most pages 3 to 9 positions below pre-panda2.1.)
Then I found it - suddenly loads of traffic (over 50% of the total) from Yahoo search for just one keyword. I love you Yahoo! Still waiting to see what todays roller coaster will bring, but lesson for me from yesterday - "Don't forget your friends at Yahoo/Bing!"