When Apple first opened the App Store back in July 2008, their review system allowed anyone to enter a comment or review on any application. No purchase was required at that time. As a result, many critical "reviews" came from those who had never bought those applications. Developers, of course, were particularly unhappy with this system which brought down the average score for almost all paid applications.
In September, however, Apple instituted a new rule in which customers could only leave reviews on applications they had actually purchased and downloaded. Existing "reviews" from these non-customers, however, remained in place.
That is, until yesterday. It appears that Apple has removed these early non-customer reviews. Several long standing apps have seen dramatic decreases in their review counts. SEGA's Super Monkey Ball count dropped from 4197 reviews down to 3710 while Namco's Pac Man dropped from 395 to 122. MacRumors forum users have noted that it has been these specific non-customer reviews have been targeted and removed.
Article Link: Apple Removes Old Non-Customer Reviews from App Store