Greece was the Trigger, Overvaluation was the Ammo
I am not one who blames Greece for much of the recent market volatility. To me volatility occurs when the string is stretched too tight and something has to give. That is where we are. Since March 2009 the markets bounced almost the maximum amount possible, what do they think will happen next. I will say that from a long-term macro viewpoint Greece is a good lesson in what could happen to the world if real investing does not replace speculation.
As to trading the markets currently, the previous floor of 1150 on the S&P will now be a ceiling. Virtually all the markets blew through their uptrend lines so technicians will now be looking for levels to be sellers.