Can the Leaders of Europe Save the Euro?

Yesterday's summit of European leaders put off action until Wednesday, another delay in a financial crisis that's beginning to sound like 2008. The possibility of so-called "contagion" goes like this: Greece is on the verge of default, and austerity measures have led to rioting in the streets. If Greece fails, private investors could lose faith in Spain, Italy and, possibly, even France, with US lenders potentially next in line. Nobody really knows the extent of the danger.  Will the Euro, designed to stabilize the continent, require that it break apart?