Three years after it started showing authorship results in search, Google has killed the project.
Google's John Mueller, a Webmaster trends analyst, told Search Engine Land that the authorship results weren't "returning enough value compare to the resources it took to process the data." Essentially, Mueller said the that it had low adoption rates by both authors and webmasters and low value for users.
Google saw "little difference" in click behavior on pages with authorship than those that did not, so it will likely be phased out. Mueller said that he didn't know if users would stop seeing author results, but already some users have reported not seeing seeing author photos.
U.S. & World
If the project wasn't a success, then it makes sense that Google would let it go. It certainly has done so with many other projects, such as Google Buzz and Google Reader.