Here's the English version of the official site of Firenze Tourism: http://tinyurl.com/5s9vv If you click on Transports and then on Bus, you get some info on the Iris ticket. Unfortunately, the sites with more information are in other languages although there are short descriptions in English of several transportation options here: http://tinyurl.com/5a25z

Hope that helps, Linda, getting ready for the GTG tonite in Toronto