So, because I do ultra-light touring I bought new puncture resistant tires for my road bike (Continental Grand Prix 4-Season, 28c), I installed them and after two minutes I had a puncture. First I thought I had punctured the tube when mounting the tires, but then I looked and not one, but TWO pieces of glass had gone through the tire. Is this just extremely unlucky or are these tires worthless?
While we don't do product reviews, note that puncture resistant doesn't mean puncture proof -- with any air based system, you're going to run the risk of cutting the tire and tube and getting a flat. Some tires are better than others in terms of puncture protection, using things like kevlar belts. The tires you bought trade off for some more the weight and handling performance versus durability to road hazards (by fitting a kevlar belt rather than whatever lighter thing they put in there) so that you have less protection from road hazards than say, a Schwalbe Marathon Plus.
Don't ride through glass and in general avoid road hazards is the best thing to do.