Yonatan Zunger, Principal Engineer at Google announced that "Starting today, you can bring Google+ Comments to your Blogger blog. Once you've enabled the feature through your Blogger Dashboard, you'll enjoy a number of important benefits"
If you decide to use the Google+ commenting system on your blog you will see activity from direct visitors, and from people talking about your content on Google+, so if there's a public discussion about one of your blog posts, those comments and replies will also appear on your Blogger blog.
With this new commenting system, your visitor will now have two options, comment publicly or privately to their circles on Google+. And when your visitors browsing blog comments, they have the choice to view all comments, the top ones, or only those from their circles.
If you have a Blogger blog, you can enable this Google+ commenting system right now. From your Blogger Dashboard select Google+ tab and then check "Use Google+ Comments on this blog". Google said that older comments will continue to appear in the new widget.
If you are a blogger who make money from your blog, then you should install this new feature on your Blogger blog so that your content will be more widespread in Google+. And I'm sure this comment system has a good effect on SEO because sharing content on Google+ has more value than in any other social media like Facebook or Twitter.