You may not realize it, but Italy is #4 worldwide in FLOSS development. So it's no surprise that Rome is switching to Linux:

'Tra mille cautele, dichiarazioni prudenti e "piedi di piombo" per le scelte, il comune comunque pare abbastanza determinato a entrare in una transizione "soft" che potrebbe durare anche a lungo ma i cui esiti pare siano ineludibili per l'azienda di Redmond. Che, con tutta probabilità, non deve essere molto contenta di come sta cambiando il mercato anche in Italia.'

In summary: Amid much caution, the city of Rome will be making a slow transition to Linux.

As usual, providers of legacy operating systems will not be pleased. One US executive says that especially in government when Linux is adopted, it's usually politically or ideologically motivated; this is probably true, and a predictable reaction to the old-fashioned methods of bribes and coercion.

Here's another article from Portalino.it with more references and details. Here's an article in English, and one in Spanish.