One of the largest complaints I see in the forums is that of webmasters complaining that their image is not showing up in the Google search results.
Did you ever think that Google doesn't show your image because they don't think it is worth looking at?
A Google Webmaster Help thread has Googler, John Mueller, reiterating a statement in the authorship Google document that "good, recognizable headshot as your profile photo" is an important part of getting included in Google's search results.
John said that "it's really more than just having your face somewhere on the photo." So just having your face in a photo is not enough and you need to make sure you get a nice profile photo so your Google authorship thumbnail shows up.
Forum discussion at Google Webmaster Help.

Comments:
Josh
10/30/2012 05:16 pm
So no more Meme Cats? Bummer!
Alan
10/30/2012 10:48 pm
So do they manually review this? or is it automated?
Praveen Sharma
10/31/2012 05:31 am
What do you think they have a profile photo review team? Of course its automated.
Mo
10/31/2012 02:30 pm
who cares ??? No one uses google plus
ethalon
10/31/2012 05:04 pm
Except for all those people that are using Google+
Pedro Matias
10/31/2012 10:55 pm
While that seems to make sense; I've seen and I'm sure you did too some logos of companies being included in the SERP.
tdthirsk
11/01/2012 07:10 pm
Launched a small site that includes my author tags on 10/28. All pages were indexed in Google with my author pic when I checked on 10/30. Same pic as used on Disqus
Abhishek
11/02/2012 07:10 am
what if someone is wearing shades in his profile pic? Will it be a problem?
Guest
11/06/2012 07:27 pm
I should probably change mine then. I'm looking at my shoes or something.