of facebooknd sheryl sanerg, the coo of facebook. >> you know what would excite me about-facebook. >> well, you can join, we ha many open os. >> rose: it is this point t is the notion that very soon, you're going to reach a billn. when will that happen. >> i don't know. >> rose: when do you think it will happen. >> i'm not sure. every day we are a little closer. >> rose: it is now 800 plus and counting. >> yeah. >> rose: is it going to be in 2012? >> i think if we do well it might be later next year, ye. >> rose: now will that be a huge celebration? >> yeah, i think-- i think it's going to be something that we're going to be really proud of. >> rose: zuckerberg and sandberg for the hour. funding for charlie rose was provided by the following: captioning sponsored by rose communications fromur studios in new york city, this is charlie rose. . >> rose: mark zuckerberg only 27 and worth an estimated 17 billion dollars started facebook as a harvard freshman in 2004. he like bill gates and steve jobs before him dropped out of college to me his company. in 2010 he was "time" magazine's pers