Here we go to the old debate of plastic vs. glass. Well I´ll take the bite. I would be really really dissappointed if they did use plastic.
Oktoberfest is a lot more than just drinking beer. It´s drinking beer with friends, in a traditional venue, with traditional and contemporary music etc. If one´s going to drink out of a plastic Maß, then one might as well not dress up in Trachtengarb. One might not as well get up on the benches and sing along to "...da liegt a toter fisch im wasser...den machma hin..den machma hin, den machma hin..." or "In München steht ein Hofbräuhaus, oins..." etc. -you get the picture. Hell, one may as well just go to a Bundesliga game and drink from the plastic cups there. For me it´s all about the stimmung. Ok, so in the old days they had stone Krugs, that´s only because glass ones weren´t invented yet. Stimmung, Stimmung! And, to take a quote from Warsteiner - "Mit guten freunden".