I thought it was very odd that Google inserted this paragraph in the beginning of a feature announcement blog post. I think it only reaffirms the inferiority complex of G+ by explicitly explaining that they are indeed a vibrant community.
Don't read into it much. Google announces its daily Android activations regularly and it has the largest smartphone share in the world.
Facebook does that too.
http://techcrunch.com/2012/10/23/facebook-announces-monthly-...
Remember when people knock Google for not announcing Google+ numbers? They are saying Google is announcing numbers because they are bad.
Inferiority complex? Seems like a "damned if you do, damned if you don't" situation. If they didn't, would you claim they didn't release numbers because they feel they have fewer users?
I don't think they're trying to imply anything. What's wrong with just giving you some numbers without any motivation behind it?
"More than 500 million people have upgraded, 235 million are active across Google (+1'ing apps in Google Play, hanging out in Gmail, connecting with friends in Search...), and 135 million are active in just the stream."