Yeah... thee grande ol' left took to the Palestinian cause as early as 1984'ish or so, sometime after Beirut, and taking out Iraq's nuclear reaktor.
There was a documentary titled "Beirut: The Last home movie" made in 1987, that I believe was nominated for an Academy Award. That film really changed things. Then you had the SF Mime Troupe winning awards for their show on the Palestinian cause. Even earlier then that, it's possible to trace interest in the movement to the 70's when Godard tried to make a film, he'd later abandon, about Fatah party. He took the rushes around to American Universities trying to drum up some business, but it never took off. Point being, it was in vogue with the hardcore radicals long before 9/11, but yea you're right, things changed once Noam Chomsky got on the best sellers list, and the counterculture movement gained an entirely new audience. Meanwhile, we know the Israel-Palestine conflict still gets a disproportionate amount of attention, compared to other world events with massive death tolls, simply because it fits an agenda or two.
The original Popular Liberation Front, and their splinter groups were actually working some psuedo Marxist angle when they started. Arafat used to spit chewing tobacco, and walk around doing his best Castro impression, and they downplayed the whole religious angle, even accept for when Jeruslame came up. They even hired the IRA to train their army.
Anyway - this essay might be of interest:
http://www.jochnowitz.net/Essays/Chesler.html