What is the objective behind "hats" ? I mean, apart from celebrating, will it reflect in your profile even after the winter bash ? (i. e. 4th Jan 13) ? your thoughts ?
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From the Winter Bash website
So most likely the idea behind them (besides fun) is to promote certain actions. A concept fairly similar to the usual badges, just a bit more seasonal/playful.
And no, after January 4th 2013 they will no longer remain. It will be a sad day for hats.