I doubt many british people celebrate it seeing as it was a way of the pilgrims to thanks the native americans for helping them get through their first year.
Wouldn't surprise me if it eventually caught on over here, like Trick and Treat, if there's money to be made out of it. Turkey TWICE a year? What a ghastly thought!
I still can't get over the amount of Americans that asked me what we do to celebrate the 4th of July in England when I was over there for it a few years back... They couldn't seem to grasp the idea that we might not celebrate losing (a boat of tea!)
I am surprised to learn that Christmas is not especially important in the US, given that it is the most religiously orientated countries of the Western world. It made a fortune for Bing Crosby.