After one year of hard work in four countries, we have LeMill version 1.0 ready, as the project schedule demands. We still consider it a preview, but most of the basic functionality is there.
What makes LeMill different from all the other learning content authoring systems that are out there? The pedagogical perspective. LeMill is not just about learning materials, but (and in my mind more importantly) pedagogically meaningful activities and tools, and a community of teachers collaboratively working on all of them.
The LeMill demo is here: http://lemill.net
And more information about the development is here: http://lemill.org