I went to my 40th (gasp) high school reunion a few years back, and I friended a few dozen of my class-mates to my then inactive FB account. I have found FB to be great way to keep up with people I see only rarely, or may never see again. Yes, some of them are daily trying to tell you all about their enlightened political beliefs, and I guess they want you to acknowledge their total virtuousness, or something like that.
I think its poor taste to discuss politics on FB- you might as well go to someones' house, whom you know you disagree with, and subject them to your political cogitations over the dinner table. There are plenty of good places on the web to go and discuss politics, and FB is not one of them.
I post a few things from time to time, but its anodyne stuff: articles/videos on musicians I like, or a picture of a mountain I took while hiking.
Cheers,
Bert