This is my latest version
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<a rel="nofollow" href="http://del.icio.us/post?url={$config.FULL_URL}/ubbthreads.php{$var_start}ubb{$var_eq}showflat{$var_sep}Number{$var_eq}{$postrow[post].Number}%2F%23Post{$postrow[post].Number}&title={$postrow[post].SubjectSocial}" title="Add {$postrow[post].SubjectSocial} to del.icio.us" target="_blank"><img src="{$config.FULL_URL}/images/social/delicious.gif" border="0" alt="Add {$postrow[post].SubjectSocial} to Del.icio.us" title="Post {$postrow[post].SubjectSocial} to Del.icio.us" /></a>
<a rel="nofollow" href="http://digg.com/submit?phase=2&url={$config.FULL_URL}/ubbthreads.php{$var_start}ubb{$var_eq}showflat{$var_sep}Number{$var_eq}{$postrow[post].Number}%2F%23Post{$postrow[post].Number}&title={$postrow[post].SubjectSocial}" title="Digg {$postrow[post].SubjectSocial}" target="_blank"><img src="{$config.FULL_URL}/images/social/digg.gif" border="0" alt="Digg {$postrow[post].SubjectSocial}" title="Digg {$postrow[post].SubjectSocial}" /></a>
<a rel="nofollow" href="http://myweb2.search.yahoo.com/myresults/bookmarklet?u={$config.FULL_URL}/ubbthreads.php{$var_start}ubb{$var_eq}showflat{$var_sep}Number{$var_eq}{$postrow[post].Number}%2F%23Post{$postrow[post].Number}&t={$postrow[post].SubjectSocial}" title="Post {$postrow[post].SubjectSocial} to Yahoo My Web" target="_blank"><img src="{$config.FULL_URL}/images/social/yahoomyweb.gif" border="0" alt="Add {$postrow[post].SubjectSocial} to Yahoo My Web" title="Add {$postrow[post].SubjectSocial} to Yahoo My Web" /></a>
<a rel="nofollow" href="http://www.google.com/bookmarks/mark?op=edit&bkmk={$config.FULL_URL}/ubbthreads.php{$var_start}ubb{$var_eq}showflat{$var_sep}Number{$var_eq}{$postrow[post].Number}%2F%23Post{$postrow[post].Number}&title={$postrow[post].SubjectSocial}" title="Post {$postrow[post].SubjectSocial} to Google Bookmarks" target="_blank"><img src="{$config.FULL_URL}/images/social/googlebookmarks.gif" border="0" alt="Add {$postrow[post].SubjectSocial} to Google Bookmarks" title="Add {$postrow[post].SubjectSocial} to Google Bookmarks" /></a>
<a rel="nofollow" href="http://www.facebook.com/sharer.php?u={$config.FULL_URL}/ubbthreads.php{$var_start}ubb{$var_eq}showflat{$var_sep}Number{$var_eq}{$postrow[post].Number}%2F%23Post{$postrow[post].Number}&t={$postrow[post].SubjectSocial}" title="Post {$postrow[post].SubjectSocial} to Facebook" target="_blank"><img src="{$config.FULL_URL}/images/social/facebook.gif" border="0" alt="Add {$postrow[post].SubjectSocial} to Facebook" title="Add {$postrow[post].SubjectSocial} to Facebook " /></a>
<a rel="nofollow" href="http://www.stumbleupon.com/submit?url={$config.FULL_URL}/ubbthreads.php{$var_start}ubb{$var_eq}showflat{$var_sep}Number{$var_eq}{$postrow[post].Number}%2F%23Post{$postrow[post].Number}&title={$postrow[post].SubjectSocial}" title="Post {$postrow[post].SubjectSocial} to Stumbleupon" target="_blank"><img src="{$config.FULL_URL}/images/social/stumbleupon.gif" border="0" alt="Add {$postrow[post].SubjectSocial} to Stumbleupon" title="Add {$postrow[post].SubjectSocial} to Stumbleupon" /></a>
<a rel="nofollow" href="http://reddit.com/submit?url={$config.FULL_URL}/ubbthreads.php{$var_start}ubb{$var_eq}showflat{$var_sep}Number{$var_eq}{$postrow[post].Number}%2F%23Post{$postrow[post].Number}&title={$postrow[post].SubjectSocial}" title="Post {$postrow[post].SubjectSocial} to Reddit" target="_blank"><img src="{$config.FULL_URL}/images/social/reddit.gif" border="0" alt="Add {$postrow[post].SubjectSocial} to Reddit" title="Add {$postrow[post].SubjectSocial} to Reddit" /></a>
Notes:-
I am only using icons (which I have contained within /images/social), so have removed the div command.
I am adding to all posts so have removed the smarty command, which limits it to the first post on a page only.
I have added "no follow" to each link
I have changed #Post{$postrow[post].Number} to %2F%23Post{$postrow[post].Number} - this allows the full post URL to go through to the bookmarks (it also ensures that the title of the post is carried over as well (which was not happening before))
I have added a few more links - I am not 100% sure which sites are the most popular.
This is not updated with the language files though. Words are hardcoded.
This needs to be added to post_top.tpl and post_side.tpl to show up in the posts for 7.2 and above.
In showflat.inc.php replace $postrow[$i]['Subject'] = "
$Subject"; with $postrow[$i]['Subject'] = "
$Subject"; $postrow[$i]['SubjectSocial'] = "$Subject";
I have tested on yahoo, google & digg - so can only assume others work as well.
Thanks to Allen for the original posts
at the moment - but expanding all the time....) 
