The FeedEntryHeader plugin adds custom text and post slug based URLs and links to your blog in the RSS feed to prevent sites from scraping your feed and displaying the content on their sites. These scraper sites usually leave out the links so some users and search engines might be fooled into thinking that the content belongs to the spammy site. You don’t need this plugin until your blog becomes very popular and you keep getting trackbacks from spammy sites.

http://www.scratch99.com/wordpress-plugin-feedentryheader/