I have created and published open source software for eDiscovery, called FreeEed. It works on your computer, on a Hadoop cluster, or on Amazon EC2 cloud.
The project is hosted on GitHub here. The discussion group for it is here.
The software is in working state, but it is an early release, which follows the common open source "approach of commit early, commit often." At this time, I am looking for feedback on what the next incremental improvement steps can be.
The software has been tested in Ubuntu. It works in local mode. It will work on a private or Amazon EC2 cluster.