Perhaps, I didn't look at it that way. Do you think they track it by visits to plus.google.com, or by activity? (ie, my phone uploads a photo ever time a take a picture, or I "share" something via reader) You don't think those would count as visits to plus.google.com, as my google account communicates with plus? I get notifications in my gmail thingy every time a photo uploads as well. Also, I do probably visit at least once a month and scroll through my pics as well. I suppose it would be interesting to see what counts as a "visit" or "active".
> And here too, I’m happy to report that we have just crossed 100,000,000 monthly active users on Google+ (plus.google.com and mobile app)
Based on what Vic said I don't think you would be counted. They don't explicitly say what does and does not count but it
sounds like you would only count when visit G+ and scroll through photos. I personally would count sharing from Reader but but instant upload from the mobile app is passive activity and should not be counted.
