It will be very interesting to see how, say, a given restaurant's Google Plus page appears in search results compared to its Yelp and/or Facebook equivalents. If Google highlights the + page in search results with rich page information (eg daily specials, updates, etc.), Yelp and Facebook have a problem.
If Facebook or someone else is unhappy with this they can just make their own search engine. I don't see an issue with Google promoting another Google product on it's own search page.
