_Google is a latecomer_ so it's quite easy today growing faster than myspace or facebook because people are now used to these networks.<p>btw the link is a good sign why g+ for apps is really missing: This service is not available -> new incognito window -> works
I wonder how many of the users actually signed up for a Google account to use Google+. They definitely had the advantage of so many existing Google accounts that just needed to have Google+ activated.