Rss Importer allows you to import blog posts from an rss feed. It uses SimplePie to parse the rss feed, and then submits each blog post to your site. Because of SimplePies advanced development, you can now import content from almost any website to concrete5- tumblr, blogspot, posterous, etc. The new posts can be added in the format of the default c5 blog, Problog by Chad, and the Blog by Scott/Jereme.
Please see the documentation to learn how to set rss importer up.