The enterprise collboaration and content management space is a crowded one. Depending on what you want to empower your workers to do, you can look at anything from basic wikis to Microsoft SharePoint to Atlassian's Confluence - to name just a few of the choices.
Cyn.in, which until recently had focused on a SAAS approach to providing this functionality, has recently launched its version 2.0 - and now it's available as open source as well.