Although this news is not official several sites are reporting that Google will require additional reviews for the ratings to be shown in AdWords ads.

When Google shows ads for companies, below the title of the ad, there will be a rating which shows the ratings for the company during the last 12 months. Previously in order for the star rating to be shown, the company needed to have at least 30 ads during that period. In addition a certain portion of those ads needed to be in the profile language.

The policy as it is has not changed to reflect the new values. However, according to reports from sites like reviews.co.uk, customers in the UK, US and EU are already affected.

It was reviews.co.uk that first reported the change. The new rules will now require at least 150 reviews in the last 12 months. For smaller businesses this is going to be much harder to pull off than before. The text for the new seller rating requirements:

New Seller rating Requirements:

150 unique reviews — each review must have been collected within the past 12 months.
Overall rating must be at least 3.5 stars or higher.

The rationale behind this move is not yet known. The assumption would be that this is to make it harder for smaller companies to buy reviews to get 30. On the other hand, with the requirement so high, Google might be expecting companies to push their customers to more actively rate them online.