According to the FAQ:
All source code is under GNU/GPL v2 or GNU/GPL v3. Pictures and artistics stuff is under CC-BY-SA 3.0.
It uses McMic's code for the website: http://projects.haxx.es/p/libregamebundle/
Those who speak French might be interested in this discussion thread as well, where the bundle's creator asks for suggestions on how to better spread the word, especially in the anglosphere.
I'm willing to translate and post any comments you may have there as well.
While those games are certainly less interesting to most people compared to the usual Humble Indie Bundle games, and one of the "games" is just pictures to fill out, I think it still has merit as a libre/CC-art game bundle.
And apart from Nikki and the robots (only one game, partially proprietary), it may even be the first of its kind!