This new post from the Mind Tree blog (at hurricanesoftware.com) asks the question "why do you care about friendly URLs in PHP applications?"
Nice URLs, readable URLs, search-engine-friendly URLs. Different names same deal. [...] Turns out this isn't all that hard with PHP - in fact it can turn into something that's very useful from more than just a readability viewpoint.
He shows how to use mod_rewrite and an .htaccess file to automatically grab the request and map it to the right place. Then, the PHP script looks at the incoming data and pushes the correct page back out to the browser. He's also included some modifications to the original idea that allow for numeric grouping and named groups for rewriting content.