Just go to www.google.com/images and click on the camera in the search bar. Then select "upload an image" and upload the picture you shared. It'll search for that specific image.
You'd be surprised how quickly pictures spread. For instance, I was surprised to find that the attached picture (from facebook) was widely spread after I posted it.
How famous have you made someone?
Just did a check as you suggested and pictures of my wife from on here have shown up on a French Swingers site, an Asian pay site and several sites suggesting she is a college girl. And to think when she posed for the camera in our bedroom she had no idea that anyone other than me would be in on the act. Here's a new one - taken outdoors and in a public place - for anyone who wonders what she looks like. How long before it reappears somewhere else...