The Midgard core libraries are distributed under the GNU Library General Public License, which permits the software to be freely used if it's dynamically linked or the user can relink it to new versions of the libraries. This is the same license used by the Linux C libraries. This licensing scheme qualifies Midgard as free software developed with an Open Source model.
The Midgard-based administration tools and usage examples in the Midgard packages are distributed under the X Consortium license, which doesn't impose any conditions on modification or redistribution of source code or binaries other than requiring that copyright/license notices are left intact. The forthcoming administration site, Asgard, will be licensed GPL.
Official Documentation is licensed GFDL which supports the Free Usage principles defined by the GPL for code.