jQuery Plugin Lab

What's wrong with this plugin?

HTML

<a href="http://www.google.com" rel="external">Google</a>
<a href="http://www.yahoo.com" rel="external">Yahoo</a>
<a href="http://www.bing.com" rel="external">Bing</a>
<a href="#" class="local">Local</a>

JavaScript

/**
 * Externalize Plugin
 * 
 * configures links that relate to external sites open in a new tab,
 * colors them red and appends an arrow to indicate that it is external
 */
; $.fn.externalize = function() {
    
    if (this.attr('rel') == 'external') {
     
        return this.attr('target', '_blank').append('\u2B00').css("color", "red");
        
    }
    
};
 
$("a").externalize().filter('.local').css('font-weight', 'bold');