Bersani has been explicitly asked to talk to other political leaders and report back to President Napolitano "as soon as possible" - we assume this will happen at some point next week. Basically, he will have to prove that his government would be supported by a majority in the Senate - the hung upper house of the Italian parliament - before he gets the definitive go-ahead.
So what happens next?
- Bersani will try to convince the other parties to back his plan for a 'minority government', which would seek parliamentary support on a law-by-law basis. It's going to be difficult. Beppe Grillo's Five-Star Movement doesn't want to do business with anyone, while Silvio Berlusconi is clearly in favour of a proper 'grand coalition' with Bersani - as this could see his party getting several ministerial posts. However, President Napolitano himself has today acknowledged that a 'grand coalition' presents "relevant difficulties".
- If Bersani does not succeed, he will have to give up his mandate to the President - who will then have to task someone else with forming the new government. This person would probably be someone from outside of traditional politics - that is, someone capable of gathering cross-party parliamentary support as Mario Monti did in November 2011. As we've noted, incumbent Interior Minister Anna Maria Cancellieri and Senate speaker Pietro Grasso are the names doing the rounds in the Italian press.
- Failing this, the only option left would be new elections. A slightly untimely outcome, given what's happening in Cyprus (think market pressure).