Facebook's networks system was a great way to target buzz-building/marketing materials to specific institutions/specific demographics. Say goodbye to all that
http://blog.facebook.com/blog.php?post=190423927130
Facebook's current privacy model revolves around "networks" ? communities for your school, your company or your region. This worked well when Facebook was mostly used by students, since it made sense that a student might want to share content with their fellow students.
Over time people also asked us to add networks for companies and regions as well. Today we even have networks for some entire countries, like India and China.
However, as Facebook has grown, some of these regional networks now have millions of members and we've concluded that this is no longer the best way for you to control your privacy. Almost 50 percent of all Facebook users are members of regional networks, so this is an important issue for us. If we can build a better system, then more than 100 million people will have even more control of their information.