The soup.io feed widget plugin allows you to place a feed from your soup.io account in the sidebar. Simply set your soup.io username in widget settings and place the widget in your side bar. This is version 1.0 so let me know if there are any features you'd like to see.

This plugin for Wordpress automatically getting your articles from soup.io

mEintopf is a feed reader with integrated one-click-reposting. It's supposed to enable your WordPress installation to become a selfhosted single-user soup.io clone.