I talked to one of the persons behind the event during a meeting in Stockholm yesterday and as you might have expected - they had been overwhelmed. I don't think their intention was for the event to be so wildly spread among the public. I think it doesn't prove the efficiency of FB, but instead shows that 1. There's too little fun in W DC and 2. It's always great fun to party at an embassy :) Also, I believe that the possibilities of swedish women attending the party helped.