In reply to Samuel Driessen.

Most of my PKM practice is inside/outside so it's all public. However, there are tools that let you filter your artifacts. Delicious allows for bookmarks to be private, and Wordpress has a private blog post function. Social networking systems, like http://elgg.org/ let you post anything as private, public or only to a select & self-created group. A lot of depends on what tools are being used by your organization and what kind of Internet access you are allowed. A challenge for PKM in the organization is how internal software platforms will be used. These may be more secure, but workers may not post as much to them because they know they'll lose the data if they leave the organization. I wrote some more about this here: http://jarche.com/2010/08/leveraging-collective-knowledge/