A block that summarize both last topics and last comments

For my site I added a block that mixes together last topics and last comments in desc order. I think that something similar should be included in advanced forum. What do you think?

Here is the code of my custom block (obviously, it can be further enhanced):

$allmessages=array();
$query_node=db_query("SELECT node.*, users.name FROM node LEFT JOIN users ON node.uid=users.uid WHERE (node.type='forum') ORDER BY node.created DESC LIMIT 5");
while ($node_array=db_fetch_array($query_node))
	{$message=array();
	$message["title"]=$node_array["title"];
	$message["link"]="http://www.mysite.com/node/".$node_array["nid"];
	$message["author"]=$node_array["name"];
	$message["timestamp"]=$node_array["created"];
	$allmessages[]=$message;
	}

$query_comments=db_query("SELECT comments.*, users.name AS uname, node.type FROM (comments LEFT JOIN users ON comments.uid=users.uid) LEFT JOIN node ON comments.nid = node.nid WHERE (node.type='forum') ORDER BY comments.timestamp DESC LIMIT 5");
while ($node_array=db_fetch_array($query_comments))
	{$query_page=db_query("SELECT COUNT(cid) as number FROM comments WHERE (nid = '$node_array[nid]') AND (timestamp<=$node_array[timestamp])");
	$num_array=db_fetch_array($query_page);
	$numpage=ceil($num_array["number"]/10);
	$message["title"]=$node_array["subject"];
	$message["link"]="http://www.mysite.com/node/".$node_array["nid"]."?page=$numpage#comment-".$node_array["cid"];
	$message["author"]=$node_array["uname"];
	$message["timestamp"]=$node_array["timestamp"];
	$allmessages[]=$message;
	}

$timestamp=array();
foreach ($allmessages AS $key => $message)
{$timestamp[$key]=$message["timestamp"];}

array_multisort($timestamp, SORT_DESC, $allmessages);

$output="<ul>";
$i=0;
foreach ($allmessages AS $key => $message)
{$output.='<li><a href="'.$message["link"].'">'.$message["title"].'</a><br />';
$output.='by <em>'.$message["author"]."</em><br />";
$output.=date("d/m/y - H.i", $message[timestamp]);
$output.="</li>";
if ($i>=4) break;
$i++;
}
$output.="</ul>";
print $output;