In this modern age everything can be stolen. Not just physical things but even intelectual like your images. One affair pop-up few weeks about about Jay Maisel’s stolen image, he sueded the guy and they settled out of court. Another photographer I admire, Jeff Revell, talked about using Google Image Search to find his images without given permission to use. He talks how easy it is to steal an image and how he proceeds in case of stollen photos. Check his original post here and it’s follow-up.
BTW Thank you Jeff for pointing out my mistake, I rewrote it correctly 😉