Frances' response was great but I'd like to add that the Trenitalia Pass is available to those who are not residents of Italy.

The Trenitalia Pass allows travel in 1st or 2nd class on all Trenitalia trains in Italy for either 4-10 consecutive days or for non-consecutive days in a 2-month period. See http://tinyurl.com/8j6mg for details.

Ciao for now! Linda