In his latest post, Sebastian Bergmann shares some information about an extension for the Reflection API included in PHP 5.

The Extended Reflection API enhances PHP 5 by providing access to type information and annotations that are embedded as doc-comments into the sourcecode.

Processable additions to the source code enable a wide range of new applications in general, and Web Services and Aspect-Oriented Programming in particular.

The wiki page for the project shares the difference between the two, including graphics to help show how they tie in together. There's even some pseudo code to get you started with the different class types, a mapping out of the API.