That appears to measure G+ for the purpose of logging in to third-party sites; and I'd guess that to most users doing so, they think primarily in terms of their

That appears to measure G+ for the purpose of logging in to third-party sites; and I'd guess that to most users doing so, they think primarily in terms of their Google account, or their Gmail account. I've heard of very little traction with "regular people" for Google+ itself; Facebook still reigns king there.