After read 11 Reasons against nofollow and Remove nofollow from wordpress comments i’ve decided to remove it. now starting from today. who comments to my blogs dont have the nofollow attribute again and the author who comment my blog will get to crawlable link. i think that’s the way how i reward to my visitor

Here some tips to Remove nofollow attribute with plugin
remove-nofollow.zip Inside the archive you will find remove_follow.php. Upload this file in wp-content/plugins and then activate the plugin in the Plugins section of the Wordpress admin
or you use Dofollow from semilogic.com

I’m using Manual Remove nofollow without plugin Here is the Step
1. Go to /wp-includes
2. Edit the file comment-template.php
3. at line 47 there is a code $return = "<a href='$url' rel='external nofollow'>$author</a>";
4. change the code to $return = "<a href='$url' rel='external' target='_blank'>$author</a>";
5. Save and you’re done