Google is introducing the star rating system across a range of its products, Google Maps for Mobile, Google Search and Google Plus Local. Local search really needs a lot of attention going forward as SEO evolves and multi-device use increases.
From Google;
We’re mapping individual ratings to the star system using the following framework:
Previous rating scale
Five star system
Poor-Fair
2
Good
3
Very Good
4
Excellent
5
The changes will appear to some users today and will continue to roll out on Google Maps for Mobile, Google search results and Google+ Local in upcoming months.
Carl on G+
http://googleandyourbusiness.blogspot.com.au/2013/05/local-businesses-get-new-rating-system.html