Surprise surprise, they went with a harder glass and lo-and-behold it's ended up brittle. This shouldn't really be a surprise to anyone who's logged some hours doing material testing, which I would assume they'd have at least one at Apple. This and the whole antenna issue really bugs me about this new phone, it seems rushed and released with minimal testing.
Also, aluminosilicate glass is not Scotty's transparent aluminum. This stuff is a doped glass that's layered (like your windshield). The closest thing to transparent aluminum is aluminum oxide (known sapphire, ruby, corundum - the color is the result of impurities, pure is colorless), you can find it in some high end watches where it's used as a scratch-proof lens (with a Mohs of 9, not much can scratch it). However, it's not a magical invinci-glass either, it too is brittle and can shatter (as can diamond), harder doesn't always mean better.