I think another part of the issue that Laura and I have had is that the word "course" tends to bring people's mind to the idea of a rigid curriculum. People automatically ask to see the syllabus and I'm not sure they grasp - no matter how many times we say it - that what we have is a rough outline and that we really are open to throwing it all away if it's not serving their needs. This is probably especially an issue for people new to peer-to-peer learning.
I don't think it's that they're not taking it seriously, it's just that "course" vs., say, "discussion group" or "club" has very different connotations and people who are already busy with work and other activities might be automatically turned off or think a "course" is not something they can fit into their current schedules.
Is anyone else having this problem?