(UPDATE: We've confirmed what some readers suspected: the 60 and 80 percent figures refer to users accessing any Google service—whether it be search, Gmail or something else—while logged in to their Google account, and do not necessarily indicate actual usage of Google+ each day or week. The 90 million figure refers not to active users, but to the total number of people who have created Google+ accounts.)
(UPDATE: We've confirmed what some readers suspected: the 60 and 80 percent figures refer to users accessing any Google service—whether it be search, Gmail or something else—while logged in to their Google account, and do not necessarily indicate actual usage of Google+ each day or week. The 90 million figure refers not to active users, but to the total number of people who have created Google+ accounts.)