Mj,
Two weeks ago in, I used copyscape to check my content and found that a Canuck site as well as an Aussie site had been using my articles, links and content.
Google was notified of the DMCA infringement prior to contacting the offending parties (just in case they tried to claim ownership first.)
In both cases, I sent a well formatted email which promised both DMCA action and host notification. In both cases, the content was removed within 48 hours.
In the first case, the content was copied/pasted word for word and posted to a page on their site by a student who'd been contracted to develop the site. The owner had no idea and was quite embarrassed to say the least.
In the second case, they'd used it in a .pdf newsletter assuming it'd never be discovered. (I love copyscape!) The site owner, a fellow in his 70's, stated that my request was "petty" but nonetheless, complied with my request, again within 48 hours.
Long story short, once they realize that they've contravened their host's content policies and that their site may be removed as a result, they tend to comply without a lawsuit.
SeoLogic provides DMCA notification guides that may prove useful:
How do you send Digital Millennium Copyright Act (DMCA) notifications to AOL, Google, Yahoo!, and the other major search engines? - Search Engine Marketing FAQ - SEO LogicŪ
Rest assured that any duplicate content penalties are short term and easily rectified by notifying the SE's of the DMCA infractions.
Good Luck.