Google Plus is now supporting the use of Hashtags. As I mentioned in Teacher’s Guide to The Use of Hashtags, the concept of hashtags was first introduced to Twitter with the purpose of creating communities around a specific content. Clicking on a hashtag will show relevant content.
Hashtags appearing at the top of a post are related to the post’s content. Clicking on a hashtag will let you explore related posts. Hashtags with gray coloring are those used by the author of the post while hashtags with blue coloring are added by Google based on the content of the post. Related hashtags help posts get discovered and build conversations around the content of that post.