The resolution of the Greek financial crisis, the Fed's decision not to overtly engage in QE3, and the rebalancing of the Russell indices drove the US equity market action today.
I believe that there will be a vote by the Greek government on Tuesday regarding their decision on the debt packages. There are a range of discussions regarding the sale of private assets, haircuts for bondholders, and the sale of public assets. There is even talk of the US or IMF sponsoring 'Brady Bonds' backed by US Treasuries.
The people of Greece will have a national referendum on the decision in September I believe, as happened in Iceland.