i've seem numerous instances of articles being used multiple times on different sites with no obvious penalties ... different sites have different nav links, content at the top, copyright info at the bottom etc. etc., so maybe jut maybe it's enough for google to not see it as duplicate content.
not sure though if there are obvious differences in the rankings for the various articles based on different key phrases
I had a client whose product.com articles were replicated in several locations on their corporate site. This resulted in the product.com listings getting filtered out of Google results - because the corporate site had greater pagerank, and thus took precedence over the "original" site.