A bit late to join in, but even I am observing a drastic fall in the positions for my targeted keywords. My site was top ranked for more or less all of my targeted keywords, it is listed in the Yahoo directory for specific categories. There has been a sudden fall in the positions for a majority of the keywords which is quite unexplainable.
What could be the reason for the penalization?
Another important thing which I feel, may be all of you have noticed, there are a lot of irrelevant results given by Yahoo SE.