New changes on Trenitalia fare and service structure, at least for the Frecciarosse (the high-speed trains). Instead of 2, now they have 4 classes of service (2nd Standard, 2nd Premium, 1st Business, 1st Executive). The fare difference between Seconda Standard and Seconda Premium is like 10-15% in some simulations I did. Seats of the latter are more comfortable, they have more privacy, a welcome drink and more space for luggage compared to the "2nd class - standard". The gotcha, however, is that I found at least 4 instances in which Mini fares on 2nd Standards were sold out, but available on 2nd Premium for prices far lower than the available 2ns standards. Which means we now have a another step on ticket shopping: looking at least two service classes to ensure the lowest possible fare.
When I searched a few trains I'll be riding in the next month, there was only one form of 2nd class, but two of 1st, as you've mentioned. This system is not in effect for all trains/routes yet. Here is a link to the trains that do have it: http://www.fsitaliane.it/cms/v/index.jsp?vgnextoid=69ac2ff4e6ee3310VgnVCM1000008916f90aRCRD . For anyone interested, here is a link describing details of the four classes: http://www.fsitaliane.it/cms/v/index.jsp?vgnextoid=00df2ff4e6ee3310VgnVCM1000008916f90aRCRD . Very interesting to me is the fact that now they will not be allowing Standard customers to visit the bar/restaurant car. It is reserved for Premium, Business and Executive classes. Not a big fan of that because although I always ride in the lowest class, I have used the restaurant service in the past when I didn't want cart food. I don't like that limitation.
The "new" Frecciarosse trains - which were first talked about almost a year ago - are very limited. Only one train is traveling each way from Milano Centrale to Napoli Centrale, with a stop in Rome. Currently these trains are not even running all 7 days of the week - so the odds are you may not even see this option in your search. But for more info, pictures, and video, see "New" Frecciarossa Train With Four Levels of Service begins service. This article will also tell you how to find the MINI and discounted prices. It will be interesting to see how this train set-up catches on. The Executive fare is more than double the Standard fare.