Hi, I just thought of sharing this plugin to you guys for you might find it useful as well.

This plugin automatically adds rel="nofollow" to all external links in your wp website (you can add exceptions in the plugin page).




This plugin will not remove old rel of a link (if any), but this plugin smartly adds necessary rel attributes. For addition this plugin can remove links on comments too.

Code: 
http://wordpress.org/extend/plugins/wp-nofollow-post/
Tested on Wordpress 3.2

Enjoy!
Hillside Reviewed by Hillside on . [WP] How to rel="nofollow" all external links Hi, I just thought of sharing this plugin to you guys for you might find it useful as well. This plugin automatically adds rel="nofollow" to all external links in your wp website (you can add exceptions in the plugin page). http://screensnapr.com/e/rnEql8.png This plugin will not remove old rel of a link (if any), but this plugin smartly adds necessary rel attributes. For addition this plugin can remove links on comments too. http://wordpress.org/extend/plugins/wp-nofollow-post/ Rating: 5