Google is using social signals generated by sharing activities on Google+ as part of their rankings algorithm. However, the importance of such signals are still of lesser impact as compared to links.
Personally, I am quite active on Google+ and I find that Google Authorship Markup, once implemented on your website, helps improve CTRs and traffic from Google. If you are not familiar with it, the markup basically pulls up your Google+ profile picture and places it beside your content in the search results.
The SEO industry is also buzzing with another signal that Google is going to use as part of their algorithm and it ties back to Google+ - AuthorRank. What it does is that it helps to rank results by looking at the authority of an author on a particular topic, and this will be based on the number of social shares or even inbound links generated by content belonging to the author. Many authors and content creators are prepping up for this by building up their profile, getting more active on Google+, and guest blogging. However, always keep in mind that whatever changes that Google makes to its algorithm, its primary goal is to return user-friendly search results so the best and the most useful content shows up.