Certainly Google+ hasn't been their first foray into the Social graph, but it's their latest, and instead of thinking of Wave and Buzz as failures, think of them instead as early social tests leading to better and better execution for each subsequent entrance. While Google may not be the unequivocal winner of the social graph in the long run, I think that it's far too early to bet against them, especially since I think they are going to outmaneuver the current competing champion FB which is essentially a gated community and will likely suffer in the long term because of it. If I was given the choice between the community in the gates, and everything else. I'd be like Google and take everything else.
With all that in mind, their vision of freeing the worlds information is currently the one leading the way, and with it will come Google + or Google['+'] or whatever future variant that they offer.