facebook at $100 billion. the most valuable company ever at the time of its initial public offering. and more valuable than citi or mcdonald s. millions hoping it will help them boost their bottom lines this morning. dan simon is live at the facebook mothership in menlo park, california, where workers are marking the occasion by working all night long. seriously, dan, what s up with that? it s 2:00 in the morning here and we re wide awake. they re having a hack a thon, an opportunity for facebook employees to basically do what they do best build, design, create. they do this periodically, an interesting public relations move as we re about to begin the trading of the stock. what they want to do is send a message to the world that they built this company on building stuff. so that s what they re doing. they posted pictures to the website showing what s going on inside some of these rooms. in terms of the fundamental challenge facing facebook in the future, it s exactly tha