When Niall Kennedy found out a creative commons licensed photograph he had taken was being misused by Microsoft, he did what any net savvy blogger would do: he replaced the image with goatse. (Ok, personally I wouldn’t have gone that far, but it definitely got their attention).
From his site:
I license my text and image creations under Creative Commons licenses in the hope they will help other people tell a better story or unleash some sort of increased creativity upon the world of content I enjoy every day. When that content is used beyond the terms of my published license I choose to take various forms of action ranging from e-mailing or sending an instant message to the person (if I have it or can query accurate information without much effort) or by issuing legal documents of copyright violations to the offensing site or host.
Read the whole story: Handling of Microsoft’s copyleft violation.