We're actually planning to push out new level sets as part of free DLC. The frequency and magnitude of those sets will depend largely on community contribution. The idea is that we can use these forums to submit and discuss levels, and then decide what should go in the next DLC level set. That way the part of the customer base that "doesn't do forums" can have access to pre-vetted good stuff as part of normal updates, avoid untested stuff, and not have to deal with their file-system at all.
Thoughts?