Moodle, the open source learning management system, has been used for MOOCs, including some of the original MOOC courses, like Connectivism and Connective Knowledge. That course was started in 2008 at the University of Manitoba and run by Stephen Downes (National Research Council of Canada) and George Siemens (Athabasca University).
Now, "Moodle for Teachers: An Introduction" will be Moodle.org's first MOOC. It is a 4 week introductory course for those who are new to using Moodle to teach. They recommend that you spend 8-12 hours per week participating in the course. Registration opens on 19 August 2013 and the course starts on 1 September 2013. There are no fees for taking the course and successful participants will be awarded a Mozilla Open Badges course completion badge that they can add to their Open Badges backpack.
Moodle partners (who use the free Moodle software but offer services for a fee) have offered Moodle Course Creator Certification courses for fees running from $200-$800 for at least five years (AKA Moodle Teacher Certificate), so it will be interesting to see if Moodle's free offering can replace those.
More at: http://learn.moodle.net