Another thought on Google+ while I'm waiting for someone to send me an invite (hint).

People are saying Circles are good. Maybe they are, but if they are, how hard will be it be for Facebook to copy them?

Until now, FB have been pretty good at the "steal good ideas from elsewhere" game. Witness buying FriendFeed and reorganising FB to be more like Twitter. If people find that Circles has a better UI than FB for organising your friends into groups, you can bet FB will soon adopt a similar UI. I'm sure they can do that faster than Google can build up FB's userbase.