Craig Mount posted a detailed analysis of a Yelp update being named the Ghost update over at Search Engine Land. In short, sometime around October, Halloween time, Yelp dropped tons of reviews in their results and in some cases, it ended up listing them as “not recommended.”

He said one of his clients “lost 40 percent of his total reviews to the “not recommended” section of Yelp” by November time. Craig checked other business and quickly found he was not alone, “some businesses had lost over 1,000 reviews” he said. Yelp wouldn’t really comment but he said “Yelp’s recommendation software and it was now recommending fewer reviews for public consumption.”

Craig’s post at Search Engine Land goes deep into what changed – I highly recommend you read it if you are at all into local SEO.

There is a lot of discussion around this Yelp Ghost update in the Local Search Forums:

Forum discussion at Local Search Forums.