Intrade puts the odds of the much broader (but time-limited) "Any country currently using the Euro to announce intention to drop it before midnight ET 31 Dec 2012" at 37% so there is some difference of opinion.
From FT Alphaville:
Buiter’s now predicting Grexit probability of 90%
Citi’s iconoclastic chief economist Willem Buiter and team are seeing a very high likelihood of a Greek eurozone exit in the not-too-distant future, and a sovereign bailout likely for both Spain and Italy this year....MUCH MORE
From their latest global update (our emphasis):
We now believe the probability that Greece will leave EMU in the next 12-18 months is about 90%, up from our previous 50-75% estimate, and believe the most likely date is in the next 2-3 quarters. As before, for the sake of argument, we assume that “Grexit” occurs on 1 January 2013, but we stress this is an assumption rather than a forecast of the precise date. Even with the Spanish bank bailout, we continue to expect that both Spain and Italy are likely to enter some form of Troika bailout for the sovereign by the end of 2012.The overall view:
Over the next few years, the EA end-game is likely to be a mix of EMU exit (Greece), a significant amount of sovereign debt and bank debt restructuring (Portugal, Ireland and, eventually, perhaps Italy, Spain and Cyprus) with only limited fiscal burden-sharing.