I've found that once students have entered their group sites (by going through a discussion or whatever), they have trouble
- understanding that they are not technically in the main course anymore (where the announcements, modules, etc. are located)
- getting back to the main course (current methods = Courses button on far left nav, dashboard, or clicking Home then the course title at the top)
I think both of these problems would be solved by simply adding a link in that list of navigation links on the group sites that says "Back to Course" (or something similar). This would emphasize that they're in a different space and provide easy access to get back.