Find this functions in your b2template.functions.php (look below for XHTML 1.0 Strict compliancy):
function waypath($content)  {
	if (!preg_match ("/<!-- no waypath -->/i", $content)) {
		//include("xmlrpc.inc");
		$client = new xmlrpc_client("/", "xmlrpc1.waypath.com", 80);
		$short_content = substr($content, 0, 2000); #send first 2000 characters of the post
		# this function has been defined further under http://www.waypath.com/apis/
		# variables can be changed to suit your own needs
		$msg = new xmlrpcmsg('inline.relatedByExcerpt', array( new xmlrpcval('23000023'), # user key (anonymous)
			new xmlrpcval("45", "int"), # last 45 days
			new xmlrpcval($short_content, "string"), # url
			new xmlrpcval("3", "int"), #style
			new xmlrpcval("10", "int"), # maxresults
			new xmlrpcval("0", "int"), # sort by relevance (1==date)
			new xmlrpcval("nothing related", "string"),
			new xmlrpcval("3", "int"), # focus (1=loose,2=normal,3=strict)
			new xmlrpcval(array(), "array"), # includedSites
			new xmlrpcval(array(), "array") # excludedSites
			));
		$client->setDebug(0);
		$result = $client->send($msg);
		if ($result->faultCode() != 0)
		{
			print "Couldn't process request: " . $result->faultString();
			return;
		}

		function print_vars($obj) {
			$arr = get_object_vars($obj->val);
			while (list($prop, $val) = each($arr))
				echo "\t$prop = $val\n";
		}
		$outString=$result->value();
		$arr=xmlrpc_decode($outString);
		return $arr[box];
		}
}


And replace with this function:
function waypath($content)  {
	if (!preg_match ("/<!-- no waypath -->/i", $content)) {
		//include("xmlrpc.inc");
		$client = new xmlrpc_client("/", "xmlrpc1.waypath.com", 80);
		$short_content = substr($content, 0, 2000); #send first 2000 characters of the post
		# this function has been defined further under http://www.waypath.com/apis/
		# variables can be changed to suit your own needs
		$msg = new xmlrpcmsg('inline.relatedByExcerpt', array( new xmlrpcval('23000023'), # user key (anonymous)
			new xmlrpcval("45", "int"), # last 45 days
			new xmlrpcval($short_content, "string"), # url
			new xmlrpcval("3", "int"), #style
			new xmlrpcval("10", "int"), # maxresults
			new xmlrpcval("0", "int"), # sort by relevance (1==date)
			new xmlrpcval("nothing related", "string"),
			new xmlrpcval("3", "int"), # focus (1=loose,2=normal,3=strict)
			new xmlrpcval(array(), "array"), # includedSites
			new xmlrpcval(array(), "array") # excludedSites
			));
		$client->setDebug(0);
		$result = $client->send($msg);
		if ($result->faultCode() != 0)
		{
			print "Couldn't process request: " . $result->faultString();
			return;
		}

		function print_vars($obj) {
			$arr = get_object_vars($obj->val);
			while (list($prop, $val) = each($arr))
				echo "\t$prop = $val\n";
		}
		$outString=$result->value();
		$arr=xmlrpc_decode($outString);
		//return $arr[box];
		$output = $arr[box];
		$small_content = explode ("<a href=\"", $output);
		$counter = 2;
		$output = $small_content[0]."<a href=\"".$small_content[1];

		while ($small_content[$counter] !='') {
			$small_content[$counter] = "<a target=\"_blank\" a href=\"".substr($small_content[$counter], 0, strlen($small_content[$counter]));
			$output = $output.$small_content[$counter];
			$counter++;
			}
		return $output;
		}
}



For those of you trying to keep your pages XHTML compliant, please replace the waypath function with this one:
(As suggested by tcervo, http://www.tcervo.com)

function waypath($content)  {
	if (!preg_match ("/<!-- no waypath -->/i", $content)) {
		//include("xmlrpc.inc");
		$client = new xmlrpc_client("/", "xmlrpc1.waypath.com", 80);
		$short_content = substr($content, 0, 2000); #send first 2000 characters of the post
		# this function has been defined further under http://www.waypath.com/apis/
		# variables can be changed to suit your own needs
		$msg = new xmlrpcmsg('inline.relatedByExcerpt', array( new xmlrpcval('23000023'), # user key (anonymous)
			new xmlrpcval("45", "int"), # last 45 days
			new xmlrpcval($short_content, "string"), # url
			new xmlrpcval("2", "int"), #style
			new xmlrpcval("10", "int"), # maxresults
			new xmlrpcval("0", "int"), # sort by relevance (1==date)
			new xmlrpcval("nothing related", "string"),
			new xmlrpcval("3", "int"), # focus (1=loose,2=normal,3=strict)
			new xmlrpcval(array(), "array"), # includedSites
			new xmlrpcval(array(), "array") # excludedSites
			));
		$client->setDebug(0);
		$result = $client->send($msg);
		if ($result->faultCode() != 0)
		{
			print "Couldn't process request: " . $result->faultString();
			return;
		}

		function print_vars($obj) {
			$arr = get_object_vars($obj->val);
			while (list($prop, $val) = each($arr))
				echo "\t$prop = $val\n";
		}
		$outString=$result->value();
		$arr=xmlrpc_decode($outString);
		//return $arr[box];
		$output = $arr[box];
		$small_content = explode ("<a href=\"", $output);
		$counter = 2;
		$output = $small_content[0]."<a href=\"".$small_content[1];

		while ($small_content[$counter] !='') {
			$small_content[$counter] = "<a target=\"external\" a href=\"".substr($small_content[$counter], 0, strlen($small_content[$counter]));
			$output = $output.$small_content[$counter];
			$counter++;
			}
		return $output;
		}
}

AND add this to your index.php inside the <head> and </head> tags

<script type="text/javascript">
function externalLinks() {
 if (!document.getElementsByTagName) return;
 var anchors = document.getElementsByTagName("a");
 for (var i=0; i<anchors.length; i++) {
   var anchor = anchors[i];
   if (anchor.getAttribute("href") &&
       anchor.getAttribute("rel") == "external")
     anchor.target = "_blank";
 }
}
window.onload = externalLinks;
</script>