The quick answer to that is "No, I don't Digg and I haven't "Reddit" and I can't see why I ever would Digg, or Reddit, or anything else that is offered on the other "social news sites". I'd much rather get my news from the morning paper and not rely on netizens to tell me what I should find most interesting. I'm just not into this "social" stuff.
I can't see how I would find this useful in my library work. It seems to me if something is newsworthy, I should be able to find out about it without going to one of those sites. Besides, most of what I saw that is most popular seems to be pretty much without any value that I can see... (Boy, do I sound old and crabby....)