Open Source Enterprise Collaboration Software

Check out 'MindTouch' - a great Open Sorce alternative to Microsoft Sharepoint - for Enterprise collaboration! http://www.mindtouch.com/

If one wants to buy support for MindTouch - once can easily buy the same

I see many of our organisations getting trapped into using MS Sharepoint - without realising that they get locked to a single vendor, and will not be having any choice to use products but from a single or limited vendors - and most importantly, with very serious security implications!! 

=========EXTRACT from MindTouch Web site======

MindTouch transforms businesses with a new class of enterprise software that cuts costs, increases revenue, and provides greater transparency across the organization. It is time for enterprise software to take a giant leap forward. MindTouch provides wiki-like ease of use with a sophisticated web services framework for rapid application development, creating flexible workflows and rapid integration. MindTouch creates a vibrant real-time information fabric by federating content from across enterprise silos, such as CRM, ERP, file servers, email, databases, web services and more.
MindTouch is an open source leader in enterprise Collaborative Networks and powers next generation intranets, extranets and knowledge bases.