Blank Target Comments is a great plugin which can converts link references in comments. It adds target=â€?_blankâ€? to links posted by comment authors and to the comment author (comment by:) link. This plugin also removes rel=â€?nofollowâ€? in the comment authors link.
They used WordPress 188.8.131.52, and they've used the plugin "Comment Quicktags" 1.0 by Owen Winkler, "Trencaspammers" by Gabriel Ortega and "Page Navigation" by GaMerZ.