We were out tonight for bit - so far so good. Some spots were closed a little earlier than planned though (was supposed to be 11 PM but the Piazza Repubblica booth was closed well before then). Lines to actually get a taste were actually quite long in Piazza San Giovanni - tons of people out at about 10 - 10:30 PM.
You get 5 tastes (assaggi) for 4 euro - which is actually a pretty great deal since the "tastes" are just a little smaller than a small gelato would be regularly. You have to buy the ticket at a separate booths though - not where the gelato is served. We saw a lot of people get to the front of lines and be confused about this!
I am sure we will the rest of the festival over the weekend and I will have some photos to post.