I'm definitely the kind of person who will post my acceptance to Facebook. For one, a lot of my friends are also applying to graduate school, and it's kind of a way to show our support for each other—if one person posts that they got accepted somewhere, we all 'like' their status and congratulate them, and it happens with everyone. I figure, we're all going through the same things right now and it's nice to know that there's people out there who are excited for you too, even if only for the split second they read your status and 'like' it If there are people out there who don't care about my acceptances, they can just ignore me or hide my status updates from their feed. Frankly, I know I have a lot of friends who I maybe don't talk to as often as I'd like but who would want to know about my success, just as much as I'd want to hear theirs, and Facebook makes it all easier
When I heard my first acceptance, I definitely posted it to FB (as "who got into grad school? this girl!!!" except with more caps-lock and exclamation points, because I'm that person). Now whoever gets accepted anywhere gets a big ol' "congrats!!" from me