Truthed. My friends company struck a deal with groupon in a strategic attempt to get more exposure, even though they sold their products at a loss. Yes their website got a large traffic spike on the day it hit groupons front page, but no, none of the traffic stuck. Just FYI.
Now that the social buying model is better understood, I feel like merchants are in a much better position to determine whether or not a Groupon deal actually makes sense for them.