iCloud share group of calendars?
When MobileMe upgraded calendars - it removed the group option. iCloud does not have a folder/group data structure.

BusyCal does let you create groups to manage your local view of iCloud (and other) calendars, but doesn't change iCloud's limitation to not have those groups appear on the server end of things.

Their blog is an excellent source to get clear and well prepared discussion on the changes MobileMe has made as well as how iCloud is different.