"The definition of groups is... everyone inside the group knows who else is in the group" This is a slightly narrow definition, the visibility of a group shoul

"The definition of groups is... everyone inside the group knows who else is in the group" This is a slightly narrow definition, the visibility of a group should be an attribute. Dan Gillmor cites a good use-case: "I'm considering a circle called "insufferable" for people I find personally annoying but whose work I feel obliged to keep track of, in any case." http://www.guardian.co.uk/commentisfree/cifamerica/2011/jun/29/google-facebook-skype http://www.guardian.co.uk/commentisfree/cifamerica/2011/jun/...