Oh yeah. I happenned to *ahem* witness a couple of 2 liter bombs myself when I was younger. A little more amusing application of gas production from metal and acid than this, but not quite as productive. What makes this a "big deal" is that it's a potential win-win situation for recyclers AND fuel cell producers, and it's on just a little bit larger scale than a 2 liter bomb.
BTW, I did know a guy in high school that went almost totally blind in 1 eye when he didn't get rid of the 2 liter bottle fast enough once and it blew up all over one side of his face. Something to think about, for you kids that wanna try this at home. Improvised munitions SEAL style are much safer... and more fun (I heard anyway).