For most of people, we use Google+ for sharing our blogpost and other good articles.And with the new features of community on Google+, you can create or join in a community.I have tested a blog post ,and if you want to share the post, you should choose the most related community and then share it.It will bring you the surprise because the people in the same community have the same interest. So start your community sharing.
Yes... a related community on G+ can deliver traffic to a site. Don't forget to respect moderator/ administrator.