http://www.articlechecker.com/
http://www.copyscape.com/
http://www.duplichecker.com/
http://plagiarisma.net/
http://www.plagium.com/

FairSare: A tool to detect misuse of content in an RSS feed.
Digital Fingerprint Plugin: A WordPress plugin to detect RSS scraping.
Tineye: A visual search engine that looks for copies of an image.
FeedBurner: Offers feed modification and analysis tools that can make detecting RSS scraping much easier.

http://www.google.com/support/bin/static.py?page=ts.cs&ts=1114905
http://info.yahoo.com/copyright/us/details.html
http://www.microsoft.com/info/cpyrtInfrg.htm