EZ FinMins say that they have not been discussing a Greek exit from the EUR but on the other hand, news from the racetrack is that the bookies have stopped taking bets on such an exit.
Greece is certainly a different case to the others but a Greek exit would significantly raise the prospects of contagion and many see the Spanish banking system as the next biggest source of concern.
I prefer to wait until after any event occurs, then wait 24 hours and see how the market reacts. If Greece exits and the EUR doesn’t fall heavily in the first 24 hours, then its a case of sell-rumour-buy-fact and I’d be buying in anticipation of a big short-covering rally. If the market starts falling immediately on a Greek exit and fails to show any signs of recovery, then I’d stay in sell-rally mode in anticipation of the next domino falling over.