Originally Posted by Webmaster Army

I'd say this pretty obviously has something to do with st. However, this just happens to be the first affected, doesn't mean it's the last. Not only does Google hate sites that are full of dupes and / or link farms they also hate webmasters doing ANYTHING to improve results. Link trades, buying links and a whole host of other things we do are not things they agree with. They will eventually tweak their algo to take into account everything they hate about you.