> Those are people who really meant to go to plus.google.com
I actually did that at least a couple of times last month by mistake, the G+ link is very close to the Inbox/Home link in GMail's web app. I cursed and hit the back button in a matter of seconds each and every time.
I went to G+ last week because Google requires it for the "Author" feature in search engine results (pure vanity, my blog posts will never show up in SERP). I went to G+ for thirty seconds this week to read the post about the guy who "cracked" a really lame DRM scheme. I don't consider myself an active G+ user at all, and yet I'm sure those "actions" (adding a URL to my profile and viewing a post) contributed to the 135 million, and I'm willing to bet I'm not the only one. Engagement across G+ per unique monthly visitor is almost certainly an order of magnitude smaller (by time on site, for example) than Facebook's.
Which means... unique user page views with 0 engagement metrics! Yay~
MAU and DAU are meaningless statistics. It's pure eye-views, that's all.
Show me some average aggregate visits per user per month, and I'll believe there's actually something happening (ie. the average number of times each unique user visited the site in a single month. Hint: for Facebook, this number is probably ~20-30).
I actually did that at least a couple of times last month by mistake, the G+ link is very close to the Inbox/Home link in GMail's web app. I cursed and hit the back button in a matter of seconds each and every time.