Of course nothing will happen. The mayor, the police department, and the police unions have already circled the wagons to head off any meaningful investigation, but this looks very high handed to me.
This happened at last weekend's Wall Street protest.
The cops corralled a small group of protesters, and then one police supervisor very casually sprayed mace point blank into the face of a woman protester in the corral.
The general behavior of the cops was a lot more rough and brutal than was really necessary, but the security of The Casino must be preserved at all hazards, I suppose. A few punched out hippies is but a small price to pay ... for something.
This is actually true to form for NYC cops. The people who own and run the city hate disorder, especially political disorder. It threatens property values. So their agents in the city government come down hard on anyone (especially anyone who isn't loaded with money) who kicks up the dust, complains, makes noise, and looks like trouble.
Someone who has been surprisingly outraged by this and eagerly updating his material is not a usual left wing rabble-rouser (e.g. Digby), but the eminently civilized and learned Atlantic columnist James Fallows.
Indeed, I agree with Mr. Fallows that the chorus of "tsk tsk tsk" coming from the Establishment pundits over these kids who refuse to be "civil" rings hollow in the face of the Establishment's obliging countenance of far right crowds at very well funded and well covered Republican candidates' debates repeatedly baying for blood, even booing an active duty soldier in Iraq. So who's the crazy nutcase here?
ADDENDUM
The Nation's Allison Kilkenny was there and has a very different take on the event from the NYTimes' very dismissive coverage. She also points out that such events are becoming more and more difficult at a time when the Right to Peaceably Assemble is ever more tightly regulated.