The Strangely Compelling Game Mechanic Powering Google+
theatlantic.com
theatlantic.com
(I realize I'm being pedantic. As a game developer, this sort of playing fast-and-loose with words annoys me in the same way people talking about "programming in HTML" may annoy you.)
Regardless, while I think it overstates the case a bit, I do think that that pop-up is actually a good driver of user behavior, at least on a moment-to-moment level.
None of those are involved here, except maybe a little bit of 1) if you consider +1 a "visual reward". I'd really expect all three to be involved before saying something has game mechanics--you can easily find each of them in Foursquare, for instance.
Oh well, at least he didn't use "gamification" :-)