This isn't that new of a thing, actually. The physical principle, I mean. Putting it in a spray-can is seriously awesome.
EDIT:
The MSDS doesn't list anything terribly nasty; the most toxic thing in there has an LD50 of 5000 mg/kg; or in layman's terms, it takes 5 grams to a kilogram of body mass to have a fifty-fifty chance of killing a rat, and likely a similar amount for a human being. So if you weighed 50 kg it'd take 250 grams of the stuff to have even odds of killing you.
I can't help but remember that movie about the people who invented a spray that made dog crap disappear, but turned out to be poisonous. "Where does the poo go? We wanna know!"