Open source DMS's similar to Confluence or MSDN Library

Question

Can anyone tell me of any open source, preferably PHP/MySQL, document management systems that are similar to:

MSDN Library:

http://msdn.microsoft.com/en-us/library/ms123401.aspx

or Confluence:

http://confluence.atlassian.com/display/DOC/Confluence+Documentation+Home

Answer 1

There wasn't really many Open Source options. So we narrowed it down to Confluence and WWHelp.

WWHelp felt too dated, very 1990's feel. Confluence, however, was perfect.