How to Catch Website Copyright Infringers
"Copyright protection for a web site is just as enforceable as it is for traditional media. U.S. copyright law states that electronic files—including web files—are copyrighted the moment they're put into a tangible form, even if they're not on display to the general public. Protected web files may include the site's content, code, scripting, graphic images, sound and video files.
'One way to determine if your site's content has been stolen is to use the search engines,' said Matt Naeger, Vice President and General Counsel at IMPAQT. 'The primary way is to see your copy in the search results. Copy-paste an extended piece of text from your web site and see what other web sites show up for that same text. Typically two sites shouldn't legitimately show up for the exact same web copy. I would say I have seen higher rates of recidivism, if you can show publication through the search engine.'"
From Search Engine Watch article via this Small Business Software post.