As someone who has tried cutting keys that way, its a little harder than it sounds. Doing it by hand, from a picture, is rather difficult (took around an hour to make an even close to working key), and while it should be possible to make an automatic cutting device fromt he picture, someone in the position to do that is probably very unlikely to break into your house (especially considering the effort to find out which key it is, then track you down and figure out which house is yours, then figure out when you won't be home).
As far as the site goes, the idea is interesting, but it seems rather bland to me. When I read it I thought it might be interesting to try, but by the time I got to the site I didn't want to do their missions any more.