I have learned that FB friendships are not indicitive of friendship/acquaintanceship in real life.
I have people that I talk to at work, church and through civic activities on a regular basis that have rejected my friend requests. On the other hand, I am friends with people I hardly know. I don't understand the dynamics behind this, but I know that people use Facebook for different reasons.
I agree, I feel like I am ignored with my status updates. People will make all sorts of comments when someone posts about their druken experience or their bowel movement, but when I post something intellectual it is like no one cares.
As for former teachers, a few of them have added me as a friend, including one of my principals. This is probably due to the fact that I have been out of school for 15 years, and am involved in acitivities with them today. Also, I am not a fan of Farmville, I help in managing our real family farm in NE Iowa.
BTW, I hate how FB has changed the info page and depersonalized it. Now for some reason, the movies, books, and activities I enjoy are now in my friends list.