I took a set of keys, a fork and a pocket knife to the front and back glass panels of the Nexus 4 and couldn't get a scratch to show up anywhere. I also slipped and dropped the phone while pulling it out of my pocket this week, and it showed no signs of my fumble.
Until I see a video, I'm not really convinced, tbh. If he has a granite counter-top, and didn't set it down as gently as the author claims, it's completely probable that it cracked. People are incredibly clumsy with phones. Glass doesn't exactly have a high thermal conductivity (nor does granite/linoleum/plastic), I find it difficult to believe the glass would expand/contract enough from body heat/kitchen counter-tops.
Which seems like a pretty good argument for not wrapping them in glass.
Too often in technology we build things that are fragile, and then blame the user when she breaks them. Tools should be designed to work with the user as they are, rather than as we would wish them to be.
Normal window glass is Mohs hardness 5.5 or so, as is unhardened steel (your fork and pocketknife); hardened steel (e.g. a metal file) is more like 6.5. That means you can scratch regular steel with glass and vice versa, with some difficulty. (Try it. I just did.) Brass (your key) is around 3 or 4, so it won't scratch glass.
There are lots of things with Mohs hardness above 5.5, including most common metals (except brass, aluminum, copper) and most rocks.
Sand is almost never made up of glass particles. It's often made up of crystalline quartz (Mohs hardness 7) which can scratch regular glass easily. Gorilla Glass has Mohs hardness of about 9, so quartz won't scratch it.
http://www.corning.com/docs/specialtymaterials/pisheets/PI23... gives its Vickers hardness as 701 kgf/mm^2, which http://en.wikipedia.org/wiki/Mohs_scale_of_mineral_hardness#... would seem to place in the 5-6.5 range of the Mohs scale, nowhere close to 9. However, Vickers is a scale of resistance to plastic deformation, while Mohs is a (highly nonlinear!) scale of resistance to abrasion, so perhaps take that with a gram of potassium chloride.
Other random places suggest sapphire's Vickers hardness is around 1800-2200 kgf/mm^2, which is substantially harder than the number Corning's brochure gives for Gorilla Glass.
As for Corning, in fairness to them they were instrumental in the development of this type of glass and own a fair few patents, so it's not just marketing. They developed it originally in the 60s, though I imagine a lot has changed since then.
From what I understand, Gorilla Glass is only scratch-proof, not tough.