There is not very much to be said. In his own words:
After the approval of this finance law, which has amendments for everything which Europe has asked of us and which the Eurogroup has requested, I will resign, to allow the head of state to open consultations.
In the Senate, the center-right still has a good majority. However with the defection of seven members of the ruling majority today, the government does not have the majority we thought we had and so we have to take account of this situation realistically.
Now, for the country’s sake, let’s hope that the left doesn’t come into power again.
UPDATE: November 9, 2011 - 12:05 pm
The day after
Things are becoming clearer and clearer. In an interview with newspaper La Stampa today, Silvio Berlusconi confirmed that he will resign “as soon as the (budget) law is passed.” He also said that, since he believes “there is no other majority possible,” he sees “elections being held at the beginning of February.” In other words he said No to any form of transitional or national unity government—which the opposition and many on the markets favour. As Il Foglio newspaper puts it, “the Democratic Party (PD) wanted a scalp, they will have a war, instead.”
But the even more important news is that Berlusconi won’t run again for office, as he himself told La Stampa, and that PDL party secretary and former justice minister Angelino Alfano would be the center-right’s candidate for prime minister.
Notwithstanding this, however, Italian borrowing costs soar... See also here and here.