You can now stop clicking the +1 button on my articles, they have no ranking benefit.
Eric Enge published an exhaustive study named Direct Measurement of Google Plus Impact on Search Rankings. In short, Google+ has no direct impact on your Google rankings, outside of personalization and of course, getting visibility out, which has a side impact of possibly getting more links. But standalone, Google+ has no direct impact on your rankings.
Didn't we know this? Yea, Matt Cutts of Google told us time and time again - but we don't believe Matt.
Here is a video interview between Eric Enge and Greg Jarboe on this study: