The Register carries an interesting story about a former employee of recruitment firm Hays who's accused of using LinkedIn to steal clients for his own agency. He claims to have been encouraged by his employer to use the site.
It demonstrates the importance of establishing clear ownership of business relationships. Increasingly that's where the real value resides. Social network sites break down the boundaries between business and personal lifestyles. We have a long way to go to fully understand what that means and how to manage it.