Response 1(50 words):
My husband works for an international company.  Recently, a new internal social networking site, reportedly very similar to Facebook, was setup for employees to use to network with one another.  Overall, it’s not a bad idea as it allows for employees across the globe to reach out to one another with HR questions, policy questions, ideas on how to improve procedures, etc.  The benefits of having so many resources at your fingertips is very valuable.
However, employees were told that they have to enroll in the social networking site and be logged on throughout the day to encourage and increase interaction.  If employees fail to enroll, it could affect performance.  As a result, this has affected the ability to focus on job duties and caused some negative feelings amongst internal employees.  Employees now spend more time than usual on the internet talking than doing their actual jobs.  How could performance be negatively affected by not enrolling in a social networking site? 
I think the idea of an internal social networking site to promote social business and enhance relationships is ideal but the requirement to participate could be detrimental in the long run.