As for former Williamsburger who headed to Fort Greene in 2002, I can say that this has been going on for almost a decade now (usually the case for anything the NYT declares a new trend). But also - without having read the article, and having no idea of the Shutes' time-frame - I think there is a distinctions to be made between early-, mid- and late-Williamburg settlers. I'm not one of those jerks who thinks that anyone who moved in 5 minutes after him is uncool (I definitely got that vibe from some people when I moved there in 1997), but the simple fact of rents going through the roof changes the personality of the place. Anyway, what I'm trying to say is that, even though the boundaries are blurry, I think that the cocaine-trust-fund kickball hipsters who everybody hates are a relatively late arrival. When I moved there, it was because it was cheap, and it was cheap because the neighborhood sucks. It's dirty, loud, and polluted. The early-settlers had it even worse, because on top of all that, it was incredibly dangerous. The stories of the parties they had sounded pretty awesome, though, like mini Burning-Mans on the East River.
Again, these are gross generalizations - like everywhere else in NY, all three waves coexist simultaneously, plus there were people who lived there before all the hipsters. But I do think that there was a post 9/11 exodus, probably because a lot of first- and second-wavers were having kids, and who wants to raise kids in a party neighborhood that also happens to be a brownzone?
The fourth wave of people who move into all of those terrible condos are really going to be the death knell, though. Kickball is going to be privatized or something.