Fewer faces will be showing in some Google search results. Matt Cutts, head of search spam at Google, has confirmed that the display of “rich snippets” will be reduced by about fifteen percent.
Rich snippets are pieces of web content attributed to a specific author, and Google Authorship allows the author’s picture to show alongside the content on the Google results page. The picture of the author is taken from the author’s Google+ profile (which is somewhat similar to a Facebook account).
The reason for the reduction is to remove the rich snippet function (and take away the increased visibility that goes with it) from lower quality sites. Google only wants the authorship picture to show for the most credible and useful web content.
Here is a link if you would like more information on the 15% drop.