The concept of word-of-mouth seems so quaint now. Recently, when a pair of my friends got engaged, I was close enough to be a lucky one who got a phone call; later when I asked mutual friends if they'd heard the news, so many people said, "I heard about it on Facebook!"
I had a thought: Is Facebook the new newspaper? It's the easiest place to make an announcement, especially the sort you want people to know about — you're engaged, you got a new job, you're having a party, as well as the not-so-fun news (i.e., you've been dumped).
I don't think announcing this kind of info on Facebook makes you narcissistic, either — but it may not be the way you want the world to find out about your life, and this still might be too public for some people.
But tell me, have you taken to Facebook to make personal announcements?