A Senate majority takes 158 seats and no party has more than 123 at the moment. The current results look like this:
Senate Seat Projections
There are 315 total seats and the total above is only 301. Although 14 seats remain, not even a Monti-Bersani coalition in addition to those 14 seats would bring Bersani's total to 158.
Curiously, it appears Bersani received a plurality of the Senate popular vote with 32% compared to Berlusconi's 30.2%. Grillo weighs in with 23.9%, and Monti at 9.1%.
If 123-104 in favor of Berlusconi over Bersani sounds strange, it is not unlike a presidential election in the US where one candidate wins the popular vote and another candidate wins the election based on state-by-state electoral votes.
Chamber Comparison to US
In Italy, both houses of parliament share duties equally. In the US, financial bills originate in the House, and only the Senate has a say in approval of judges and cabinet-level positions.
"AC" writes ..."Most likely Italy will go back to vote within a couple of months, probably after changing the electoral law."