rlange - 3:56 pm on Feb 8, 2012 (gmt 0)

Author information in search results [support.google.com]: If you want your authorship information to appear in search results for the content you create, you'll need a Google Profile with a good, recognizable headshot as your profile photo.

They use the word "need", but I'm not entirely sure if it's a requirement or a very strong suggestion.

--
Ryan