There are many Facebook apps which facilitate the publishing of their posts on fan pages and profiles but most really do not work that well. After much trial and error the most user friendly WordPress Plugin I have found for Facebook is Simple Facebook Connect.

Here are some of the feature of Simple Facebook Connect:
Enables your site to connect to Facebook with JS SDK
Implements OpenGraph tags, entirely automatically
Comment using Facebook credentials (with Facebook avatar support)
Automatically Publish new posts to Facebook Profile or Application or Fan Page
Manually Publish posts to FB Profile or Application or Fan Page
Integrate comments made on Facebook back into your own site
Login with your Facebook credentials, optionally using Facebook avatars instead of Gravatars
New user registration with Facebook credentials (using the Facebook Registration Authentication system)
Facebook Photo Album integration in the Media uploader
Like Button and shortcode
User Status Widget and shortcode
Live Stream Widget and shortcode
Fan Box Widget and shortcode
Fan Count Chicklet and Widget
Activity Feed Widget
Share button and Shortcode (reworked version of Like button, as Share button is no longer supported by Facebook)

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