For whatever reason you might not want rel=nofollow in all links in your blog that commenters leave. I certainly don’t. I only approve comments that are useful/no spammy sites. So why be harsh and put a link condom on?

Making all links in your word press blog (esp links in comments) not have a rel=no-follow is quite simple. Just edit a couple of files:
Warning: Editing files can **** up your WordPress install. Only continue if you know what you are doing. Make backups!

• Open wp-includes/functions-formatting.php, search for “rel” and find all “nofollow”‘s and remove them. There are quite a few. Don’t just search and replace though, check them all one by one (About 5/6 in total)
• wp-includes\comment-functions.php – line 366 (for me, anyway). Remove the “nofollow” bit :)

This doesn’t mean you can just now spam away on this blog and get free backlinks… (they’re all moderated anyway).

This also removes rel=no-follow from trackbacks. Be carefull! Rel=no-follow was introduced for a reason…