I tweeted earlier that due to Google+ not currently being open to all to register there is the potential for participants in #change11 to be disenfranchised, unable to access content and interaction of co-contributors. Even though it was pointed out that all registered users get 150 invites to distribute, Google at the moment is saying:
Already invited? We’ve temporarily exceeded our capacity. Please try again soon.
Perhaps this is one element of an open course, some things might not be accessible for all participants. But there is a distinction to be made about choosing not to participate due to not wanting to use a particular medium or service and not being able to access a service.