[Don't get out as much as I used to!]
I heard this chant for the first time in New York while watching the videos of the conga line snaking through the crowd at Zuccotti/Liberty Park before the police went on their riotous rampage on Saturday night.
The video above shows what may be the first time it was used in New York, on Wall Street, on December 13, 2011. It's great. A report from Chapel Hill from last November:
Sure seemed like it! And note well, the New Yorkers are far more enthusiastic when using this chant than are their European comrades.
When the police crossed the street towards the building, about fifty of us gathered in front of it, chanting “A—Anti—Anticapitalista!” The officers hesitated—what was this strange incantation?—and withdrew. That chant cast an enchantment, magically protecting the occupation.
Also check out The Story of Stuff if you haven't seen it.