On PHPFive.net, there's this new tutorial dealing with the creation of a dynamic Google sitemap with the help of SimpleXML - basically, the paths for Google to follow to best index your site.
This tutorial demonstates the PHP5 SimpleXML extension by using it to update a Google sitemap dynamically. It assumes that you have a basic understanding of PHP and are familiar with XML. SimpleXML represents a XML file as a native PHP object and this makes it a good deal easier to work with than either DOM or SAX. Using SimpleXML you can read, write or iterate over a XML file and access it's elements and attributes.
Whilst there are free online sitemap generator tools available on the Internet that allow you to create an XML sitemap which can be submitted to Google sitemaps. In order to better demonstrate the SimpleXML extension to you, we will do something useful and create a PHP function that will parse and prepend new entries dynamicly to a web sites Google sitemap.
He gets right down to it, illustrating what a sitemap looks like followed by a simple sample script to create it for that data. SimpleXML makes it a snap to generate the properly formatted XML and split it back out for Google's bots to consume.