I just stumbled across this and it sounds ominous:
http://www.telegraph.co.uk/finance/f...on-outcry.html
The Greek government just made a sudden announcement of replacement of the military chiefs. That smells like they fear a military coup, or want to get people in place who might go along with some "extraordinary security measures" or some such. The call for the referendum seemed inexplicable, but if something like this is brewing behind the scenes, it would make sense.