Reflections, Ramblings and Action. ©2005-2009 | 
Corporations jump on the bandwagon of social networks. Four years ago Andrew McAfee wrote the book "Enterprise 2.0: The Dawn of Emergent Collaboration". Just recently, the Salesforce.com founder and CEO Marc Benioff asked in his techcrunch post, "why isn't all enterprise software like Facebook?"
And obviously software vendors of company directories and LDAP using services add social features to their functionalities. It is an obvious evolution, because Facebook isn't really a social network. It is more like a classic people listing service for your social life - a social directory service. Facebook has taken the good old company directory and made it a public directory with social features. It is centralised and locked, very much like the one at work, though you have more freedom changing and using it for your purposes.
