Stack Overflow-like Open Source Q&A Systems for Download

Few days ago, we have mentioned Qhub, which is a simple way to create a Q&A website. However, hosted version is only available to us only. How about a Q&A system that is open source and also let us install on our own server? Our readers have pointed out the following Open Source Q&A Systems.

OSQA is an Open Source Q&A System written using Django. Users can ask and answer questions, comment and vote for the questions of others and their answers. Both questions and answers can be revised and improved. Questions can be tagged with the relevant keywords to simplify future access and organize the accumulated material. OSQA can be downloaded from the project’s GitHub repository at http://github.com/rickross/osqa. It is under GNU General Public License.

Shapado is another Stack Overflow-like app written in Ruby on Rails, mongomapper and mongodb. It is available under the GNU Affero General Public License. Shapado can be downloaded from Gitorious at http://gitorious.org/shapado.

Requirements: Django or Ruby on Rails Framework
OSQA: http://osqa.net/
Shapado: http://shapado.com/
License: GPL License