Today at playgroup, she ran over to one of her friends and clawed her face in a grisly attack. She whacked another kid in the head. She scratched my arm quite deliberately when I was getting her out of the car seat this morning.
I'm pretty sure this is just a developmental thing and that my job her is to discourage these violent tendencies as best I can. For a long time, she's been beating up on the cat and we've been practicing "nice touch." And I think we've started to see some progress with "nice touch" and the kitties. Now we just have to get it to generalize to all other living things.