What he did was to get out of his car and ask (twice!) why his car was being searched-- he was on his way back into Canada, and he was dealing with American border guards.
Contributions to his legal defense fund can be sent here.
papersky explains that living in a free country means not being afraid of arbitrary attack from the police.
pecuniam on why letting governments get away with torture is a disaster.
comodorified on the emotional meaning of throwing someone out, unprotected, into deadly cold. And an update on why Watts survived this-- he was dropped off on the Canadian side, not far from Canadian Customs.
Digby on why having police that you need to treat like thugs is a bad thing.
In the comments to the various posts about what happened, there are some who say "I've crossed the border any number of times and nothing went wrong, so I'm not believing that this was an arbitrary abuse of authority." I've recently read The Black Swan by Nassim Taleb-- the premise is that people wildly underestimate how often unusual events with large consequences happen.
It isn't nonsense to assume that your experience has something to do with how things usually are, but it needs to be tempered with information from other people, and a check for asymetries. Does it make sense that only the low status people behave badly?