Adding link post format to theme and permalink to rss feed

as a self-appointed thematic support guru, i can simplify your first filter:

/**
 * Override the post title logic for post format 'link'
 */
function mikewillsthematic_thematic_postheader_posttitle($posttitle) {
    if (has_post_format('link')) {
        $posttitle="<h2 class="entry-title"><a href="";
        $posttitle .= get_post_meta( get_the_ID(), "post_format_data", true);
        $posttitle .= '" title="Direct link to article" rel="bookmark">';
        $posttitle .= '&#8734; ';
        $posttitle .= get_the_title();   
        $posttitle .= "</a></h2>\n";
    } 
    return $posttitle;
}
add_filter('thematic_postheader_posttitle', 'mikewillsthematic_thematic_postheader_posttitle');

you might also want to do a test for the presence of the meta URL before you put it into the link. i don’t think your solution looks excessive. you want to change the post permalink in 3 places, so i’m not surprised that you need 3 filters. kind of wonder why that isn’t default behavior for link formats, but i’m not versed enough in post formats to know why WP did it that way.

afaik you cannot filter the post title via WP. when you have a solution (or before) please post at the thematic forums: