We have a new group to discuss developer- and user-level documentation, mainly on http://doc.silverstripe.org and http://api.silverstripe.org. http://groups.google.com/group/silverstripe-documentation
This is a response to this blog post: http://silverstripe.org/calling-for-help-in-documentation/, and mainly serves to coordinate the effort for now, but is also an open forum for suggestions and other comments. You're welcome to join in! :)