Social Networking in Organizations

I've not - so far - had the opportunity to experience or see Social Networking being implemented in the context of business (organizations), but I am keen to find out how exactly it would make a difference to an organization and whether it will cut across barriers like reluctance in the workforce (as they've to expose their mail transactions for such a software to be effective). Anyways, I've prepared a quick mind-map of the basics in case you're interested. If you've had the opportunity to work on/use SNA tools, please do leave your comments and experiences here.