There is pending congressional legislation that will remove significant copyright protection from all works of art if it is enacted.  The Orphan Works Act of 2008 makes it possible to declare a copyrighted work "orphaned" if an infringer says that he is unable to locate the author based on the infringer's idea of a reasonable search.  If a company wants to use your images, all they have to prove is that they used what they determined as reasonable methods to find you.  When they don't find you, they can use your images for whatever they want, without your approval or compensation.