Transparency International has been compiling statistics on countries' corruption for years now, and for years Italy has made a figuraccia (a terrible showing). 2011 is no exception.
Although one may be skeptical of these organizations, their agenda, and the resulting data, Italy's abysmal rating is fully consistent with what I observed first-hand in twenty years in Italy. Which is why I no longer live there, nor would I return.
The countries that do best, as usual, are the Scandinavian countries. My own country, the United States, does much better than Italy, but not as well as one might expect, and this is also in line with my experience.
See the classification for yourself here.