Don't have any data per say on page rank but I don't find it to be a big problem. To me it appears as if the first site Google finds with the content is considered the source. I don't think Google penalizes for duplicate content. It just doesn't reward. So if some of your posts are found first then that is a plus for you. If not it is a plus for someone else but either way I don't see it as a negative. News Articles are copied all over the place from the AP and I don't think it hurts their PR ratings.. Just my two cents.

Kevin.