Tough deal. Not the first time I heard that story. I take a somewhat foolish and nieve approach.
My freelance clients pay a fair amount of money to own the photos I take. They could have them made into billboards for all I care. My time was well paid for. Why should I chase down a client that had my photos printed at wallmart? My editorial work for the paper is owned by the paper. I can show the work, but I can not have the photos that were published reproduced. Again; that is fair because I am paid well.
As far as my personal work goes (the stuff you guy's suffer through) you can have it. If someone asked or stole an image off of my online gallery or whatever; I doubt that I would care. The time spent was for my understanding of the CRAFT. When I post or show a photograph I gained a lot more then some fool who claimed it as his own and made 500,000 dollars. Then again; I am no Jay Maisel. I can see things getting dodgy if you are famous.