Google has just released SideWiki for the Firefox Google toolbar (oddly it does NOT work with Google Chrome yet) which allows GMAIL registered users to post comments on any webpage for other SideWiki users to read.
There are certainly lots of factors with this feature that remain to be seen as to their usefulness, but for those irritating article thieves, we now have a quick way of exposing and possibly diverting some traffic back to your original resource.
Just post a SideWiki review on their webpage saying "This content has been unlawfully taken from my own site, which I am the author. Please visit the original document for a more accurate version and a video on this very subject at www.myoriginalarticle...."
or something to that effect.