Pocket Guide to Google+: Link to Post, top influencers and video by Stephen Hovnaian. The following is a quote from Stephan as to why Google +
Google+ is a social layer that sits on top of all Google’s products (search, Gmail, YouTube, the ads you see on web pages, everything). Connecting your Google account to your various social profiles, blog posts, etc. allows Google to learn what you know the most about, so it can recommend you to other users looking for the same thing.
I’m a Google fan Girl, He’re’s Why: Post by Denise Wakeman on why everyone should consider being on google+