Hey haven’t you heard of Virtudex.com? It’s the best business social network. Invite only so here is the pass code - 1z1code Lets see they have Blogs, Groups, Personal File manager, Homepage news feeds with RSS, the best privacy settings I've ever seen on a social networking site...
Facebook isn't business focused, they offer no business tools. Just the fact that it's a "social" network psychologically reduces it's effectiveness as a business tool. It's hard to separate the business from the pleasure on facebook.
