One of my sites: http://www.printmypics.net was duplicated completely by someone else -- the content management system, menus, exact verbiage in the descriptions and reviews etc. My primary concern in duplicate content issues with search engine rankings. Legal action would be my last choice and I'm not sure it would even work. What recourse to I have? What tone should I use when contacting them? Just looking for feedback from anyone else who may have experienced this. Thanks.
Personally, I would send off an email to Google, Yahoo, MSN, etc. and let them know about the duplicate content. Maybe they'll take action to drop them out of the search engine results, thus killing their traffic.
You can try checking check who owns the domain the site is hosted on. You can also try contacting their host to see if they will take it down.