OK .. first of all you need to get a SVN copy of Thematic.
Sorry for this, but I'm too lazy to rewrite the whole code :)
Then try this one:
function my_postmeta() {
$postmeta = '<div class="entry-meta">';
$postmeta .= thematic_postmeta_authorlink();
$postmeta .= '<span class="meta-sep meta-sep-entry-date"> | </span>';
$postmeta .= thematic_postmeta_entrydate();
if (function_exists('tweetmeme')) {
$postmeta .= ' <span class="meta-sep meta-sep-tweetmeme">|</span> ' . '<span class="tweetmeme">' . tweetmeme() . '</span>';
}
if (function_exists('fbshare_manual')) {
$postmeta .= ' <span class="meta-sep meta-sep-fbshare">|</span> ' . '<span class="fbshare">' . fbshare_manual() . '</span>';
}
$postmeta .= thematic_postmeta_editlink();
$postmeta .= "</div><!-- .entry-meta -->\n";
return $postmeta;
}
add_filter('thematic_postheader_postmeta', 'my_postmeta');
The code itself is working. I can't tell you if the buttons will work and if the markup is the right one.
Chris