Hi, Because it's good to let PR flow naturally, I generally chose to let my social media channel pages/fan pages get some of it. But: I have Facebook, Twitter banners on all my pages and I'm thinking whether to make them "nofollow" or not. If I make them "nofollow", then more PR could flow to my internal topic pages. Not sure... What do you do? What would you do?
Interesting concern. I never nofollow links excerpt for rare situations. Be (or appear to be) as natural as possible, and don't try to game Google. I don't worry about links to Facebook; it's already so trusted it's not as significant a link to an unpopular website.
Now correct me if I am wrong but are not no follow links mostly (in Googles case) a way of telling Google something is "not quite right" or not as natural as it could or should be? Now thus saying stop and think a wee mo. It's flagging something but what is it flagging? Well argue away on that one if you like ?.... Are you / we sure 100% it is flagging at the other end what we think it is flagging? Food for thought eh?
If your Facebook is a quality representation (as in, you engage with users and it's somewhat of a secondary content production or testing ground) of your company / website... I don't see why you would 'nofollow' your main link. Since the association is valuable, I would let it flow.