Trolling means posting something insincere to elicit a response. The point of trolling is to fool the target into investing time and emotion into responding seriously. Insincerity is the defining aspect of trolling, and seeing the victim's response is how the troll gets his kicks. What the asshole kid in this story was definitely stalking, but it wasn't trolling unless he posed as an antisemitic hate-filled stalker for the malicious fun of watching the victim react. Unlikely. Honestly, I think the guy is being way too easy on the kid by calling him a troll. The kid is a stalker. The police should have been called, because he's likely to do it again.
I think the terminology has evolved a bit(at least among the younger generation, those who are trolling almost as a hobby), although it might just be me since I don't spend time around communities dedicated for trolling.
Are you aware of Encyclopaedia Dramatica for example? Many of the 4chan stunts are done "in name of trolling" and "for the lulz", when infact they may involve stalking the subject and even physically being in contact. I think in cases like these it's first and foremost a social thing for the "trolls" to stir shit up, the more the better.
Or perhaps I'm just ignorantly stretching the term.
Eh, I wouldn't call what 4chan does "trolling." They get their lulz by hurting people, both to prove they can do it and just to enjoy inflicting pain. They usually want their victims to know exactly what's happening, who's doing it, and why.
I hope trolling doesn't come to mean any kind of maliciousness, because it won't enrich the language much for it to take on such a broad meaning. Thanks to human nature, we already have a pretty comprehensive vocabulary for obnoxious behavior. Trolling in the narrow sense is a handy addition for a behavior that has emerged as an everyday fact of life in the internet age, but trolling used in the broad sense is usually a lazy replacement for a better expression.
Edit/PS: To be clear, what 4chan does is bullying. Harassment, spreading embarrassing information, vandalism, insults, reputational attacks: there is nothing novel about this pattern of behavior. In second grade (the early '80s) my entire elementary school was taken out of class so we could watch a short film about bullying. If I remember correctly, a kid was bullied until one day he fell over dead because he didn't want to live anymore. Cheesy, but it shows that 4chan's methods and intentions aren't new and don't merit a new name. The only novelty is that the bullies' unashamed voice has been added to the conversation, so now we know they do it for the lulz. (Which is what everyone assumed about bullies anyway until someone invented the idea that bullies were abused and miserable themselves, which became the new conventional wisdom until it was challenged recently, and now I think even the touchy-feely types think it's really all about the lulz. But I digress.)
