Sign-ups are not active users. Google reports sign-ups. Facebook & Twitter report active users. Just one of several perils I cover in this piece, for those trying to measure Google+ growth against competitors.
Thanks +Mrinal Desai+Danny Sullivan Nice to see that someone else get's it. Gplus is all about a quality experience for everyone. Spammers, shills and Spinmeister' s are not happy. Lot of embedded Facebook marketing / SEO types are not happy with the numbers. Well I can only see this as a good thing (TM).