A few months ago, the .NET world was surprised with a magnificent tool called "Glimpse". Today I'm pleased to release a first draft of a PHP version for Glimpse! Now what is this Glimpse thing… Well: "what Firebug is for the client, Glimpse does for the server... in other words, a client side Glimpse into whats going on in your server."
He includes a of how the introspection works and some sample code using a phar to add it to your PHP application. You can see it in action in this screencast based on the PHP Azure Contest website. He also shows one very cool feature that allows for cross-device tracking of requests. You can find this PHP port of Glimpse on github.