I've never done it, but it looks like it has to do with a few valid pieces of coding that you place in your article/on your page. There is a great write-up and a plug-in suggestion here:

http://clickbump.com/rich-snip.....r-ratings/

The actual coding that needs to take place in the post/page are covered in this link (if you don't want to download the plug-in):

http://schema.org/Review

When Google crawls your site and sees this code, it knows to treat it as a review and will give your article the option of being reviewed by Google visitors and searchers. Hope this helps!

Any idea how some organic posts that appear in Google Search results have STARS under them (1-5)? Any idea how one replicates that as well? Or is this a paid thing?

Thx,

Sam