From Der Spiegel:
Greece's economic problems are massive, with protests against the government being held almost daily. Now Prime Minister George Papandreou apparently feels he has no other option: SPIEGEL ONLINE has obtained information from German government sources knowledgeable of the situation in Athens indicating that Papandreou's government is considering abandoning the euro and reintroducing its own currency.
Then there's the always insightful Tyler Cowen, writing for the New York Times
…if any one euro zone country were to start exiting the euro, there would be bank runs on the other fiscally ailing countries. The richer European Union nations know this, and so they are toiling to keep everyone on board. But that conciliatory approach creates a new set of problems because any nation with an exit strategy suddenly has enormous leverage. Ireland or Portugal [or Greece!] need only imply that without more aid it will be forced to leave the euro zone and bring down the proverbial house of cards. In both countries, aid agreements already are seen as a “work in progress,” and it’s not clear that the subsequent renegotiations have any end in sight, because an ailing country can always ask for a better deal the following year.