Panthro - 4:57 am on Jun 9, 2012 (gmt 0)
I've not taken the time to do a scientific study on this yet, but when searching across niches on Google Local, it seems that reviews from Google+ users are most likely to appear first on the list when sorted for "Most helpful".
I'm sure Google policy has its ideas about why a review from a verified Google+ user should always be listed first when available, but IMHO these are not always the most useful. In at least some cases, these "most helpful" reviews were not voted most helpful either, under the old Google Places format.
Maybe you all can share your observations?