John Cavers sent along this question, which I have seen people asking a lot recently: I see some of the listings below have a link to the "Google+ page" and others do not. How is this link made on these listings?
Prior to the rollout of the review box pop-up in the main local search results, all of the pinned local results linked to the business's Google+ About page to either read or write a review. If the business had a G+ social presence there was also a link to their G+ Posts page. However, the review popup rollout changed that -- creating a confusing mix of links in the local serps.
Google has several "rules" that they use to show or not show the Google+ page link in the main search results
1) If the business has no reviews and no social upgrade, they show the Google+ "About" Page link.
2) If a business has both reviews and an upgraded Google+ page, Google shows a link that goes to the "Posts" page. (The review link opens the review box.)
3) If the business has reviews and no social upgrade, Google only shows the Review link and not the the Google +page link.
If a business has no reviews but a social page, I am not sure what they show. If you have an example of that please forward it so that I can see what shows.
(Photo by Gareth Simpson and used via Creative Commons license.)