A Filter to Block Copyrighted Images?

Slashdot mentions a new filter called iShield that can automatically recognze porn based on the contents of the image (not the URL or text) and block it from appearing in your browser. If iShield can do this for porn, how long before a similar filter is developed that can censor copyrighted pictures based on content? Would this be good (less lawsuits) or bad (fewer images, especially if such a filter was imposed) for Google and search engines generally?