bill - 2:57 am on Sep 28, 2009 (gmt 0) We've had a number of threads about RSS feeds & duplicate content [google.com].
Welcome to WebmasterWorld nstaylor.
RSS aggregation where the content is the same is obviously duplicated, and if Google has indexed the source before, your duplicate is counted as SPAM towards your site.
Search engines don't work that way. Duplicated content penalties won't be incurred for RSS syndication. You simply won't be credited for that content as being original. In that sense it won't help you, but it's not supposed to hurt you either.
We've had a number of threads about RSS feeds & duplicate content [google.com].