The key word is "resistant": it
resists scratching - better than ordinary glass does - but it's not scratch
proof. So it's still possible for it to get scratched, just less likely. Corning's
data sheet for Gorilla Glass is informative. Note that they do not claim that it
cannot be scratched but they do say it has "High resistance to scratch damage", and they also claim that scratch damage is less visible (see the photos on the second page).
If you look at Corning's
"Products With Gorilla" page you will see that the world and his dog use it in the smartphones. That list includes just about every Motorola smartphone phone, so it's by no means unique to the Defy. Interestingly, Corning don't list Apple, although
Wikipedia states that the iPhone was the first volume commercial use of Gorilla Glass, it having been sitting around waiting for someone to find a use for it since the 1960s.