The place to learn of randonneuring events and brevets in Italy is http://audaxitalia.com/ which is the website of Audax Italia.
The site is in Italian but it's easy to navigate. If you have questions you can contact the organization by clicking on CONTATTA and entering on the form your name (nome), email address, and your message (messaggio).
If you would like to register for email announcements, in Italian (only), click on NEWSLETTER and enter:
Si (yes) to receive the newsletter
click on INVIA to send
The home page features many of the events and under the BREVETTI button you can find a detailed calendar which is divided by ACP (Audax Club Parisien) and non-ACP events.
Photo: Italian riders on a brevet; as you can see most of the events in 2008 were in northern Italy