Lee Odden has a great overview on duplicate content issues.
He is blogging various sessions from the Chicago Search Engine Strategies conference.
Here are the bullet points from just one of the speakers on the session (Shari Thurow), and I bolded one of them
Ways that search engines filter out redundant content:
* Content properties – removes boilerplate elements and reviews whatâ€™s left
* Linkage properties – Is a press release on the wire service and the press release on a web site duplicate content? No, because the linkage properties are distinctly different, even though the content is the same
* Content evolution – most content does not change. High average page mutation – news site. Low would be a manufacturing site
* Host name resolution – If the hostname resolves to the same domain name, one version of the redundant content will be selected as the canonical url
* Shingle comparison – References Andrei Broder. Shingles are word sets. The more shingles that a document has, the more likely it is duplicate content.
There is very little difference between article marketing and press releases.
The big difference is in the other navigation elements on the page.
If you are using one of the very popular article site scripts, work hard in differentiating your site from other sites using the same script, especially if you are receiving the articles from a similar source such as Article Marketer.
The same would be true of people using RSS feeds from Article directories. If you are not doing anything to change the linking structures of a page and relationships between content, you are not going to achieve the results you want.
Do take the trouble to pop over to Lee’s blog and read the full article:- Duplicate Content and Multiple Site Issues