A few days ago I noticed that small adsense sites that have ranked great for several months all of a sudden have gone way down the rankings (top 10 sites, and they are now not even in top 100).
If I search on the domain name for these sites it still shows up, so the sites do not seem to have been de-indexed.
I know that google makes this 'dance' once in a while, but this is for a lot (I've checked around 20) of my sites at the same time.
Have you tried this?
If this is just a 'dance', when do you think they should be back to normal?