If you've been thinking of jumping into the wide world of obliterating small fuzzy creatures in WoW, now is a good time to start, because since 3.0.8 went live, it's official: killing critters is cool. Pest Control is a new achievement introduced with the patch that gives you credit for killing the creepiest and crawliest of critters on Azeroth, the insects, arachnids, snakes, and other such vermin. You've probably accidentally killed these fellows with a stray Fan of Knives or Pestilence or what have you anyway, but next time that happens, you'll get credit.
If you're a critter lover and need to assuage your guilty conscience, have no fear. You can always do To All The Squirrels Who Shared My Life while you're killing the pests. That way there's some sort of balance. You can be a lover, a killer, or both. Rather zen of Blizzard, don't you think?