You can use the links to the right on the dashboard page of your Google Webmaster's Central account, use the report spam link and mention that it's duplicate content, I've had success using that method. Also review the official Google Webmaster Central blog for more details on this matter. http://googlewebmastercentral.blogspot.com/2007/06/duplicate-content-summit-at-smx.html
It is much easier to do it with msn and yahoo than it is with google. You will have to mail them or fax. Regards, AHT