[notabel]

I don't find it entirely impossible. After Startup School I talked to Adam D'Angelo about spam on facebook (largely because I'd never seen any); he said that there is a lot of spam activity, but that internal safeguards prevent most of it from ever being visible. If the researchers were using internal, pre-filter datasets, their claim is reasonable.

[danw]

Good point. I was concerned that the researches might be counting messages to groups as spam.