When Google rolled out G+ Local with Zagat reviews they changed the ordering of review content from time based to most helpful. As part of that ordering they added a new category of reviewer known as a Top Reviewers. These were folks that had reviewed a large number of locations. Google also added the ability for a business (and I presume its many managers) to leave reviews of other businesses.
See it on Scoop.it, via Google Places Optimization & Local SEO News
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