Same thing here. A week ago my most important website doesn´t even show for my main keywords. Today, it hit the other 4 major sites I have. Guess i´ll just stop making quality content websites and start making those shitty keyword filled websites and focusing on gettin MSN and YAHOO traffic.
Well, Google is still doing fine for some of my sites and keywords while other keywords dropped down and pages disappering so, I think it's google updating their logarithm to be more restrict, Maybe?