There’s some debate on SeoMoz / Hacker News. I thought I’d share my experience, since it seems in conflict with the two main arguments.
The first being what the correlation between Google+ 1’s and search ranking is, the second being that Google just wants everyone to write quality content.
Here is a chart from the last eight months of this site, you can see readership increasing over time, with large bumps from things that did well on Reddit, HN, G+, Twitter, etc (usually one, but not all of the above). These range up to 50-100 twitter/g+ shares:
Google Analytics has this nice “Social Media” chart which confirms the same story:
At the same time though, you can see the “Search impressions” and “Search traffic” charts are pretty much flat:
The lesson I’d take from this is that writing good content is important, with the beneficial effect of making Google irrelevant, as, in my case, it’s now the source of ~10% of my readers.