Recently Google has introduced Google+ comments to bloggers blogs, now blogspot users can easily enable Google+ commenting from their dashboards and allows their readers to comment using Google+ account credentials.
Using Google+ Comments your readers will be getting option to comment publicly or privately to their G+circles and while browsing blog comments, they can view them all or just the top ones or only those from the people in their circles. Your commenters will only be seeing the comments they have permission to see and proving these controls will encourage more meaningful sharing will bring traffic towards your blog.
For getting started with Google+ Comments, visit the Google+ tab of your Blogger Dashboard and check “Use Google+ Comments.” All older comments will continue to appear in the new widget.