Gonzalo Ayuso has a new post to his blog today talking about a regular expression-laden script he's some up with to reflect over a PHP file and pull out the document's comments (PHPDoc-style).

I want to parse PHPDoc code. Let me explain a little bit what I want to do. Imagine a dummy function documented with PHPDoc. [...] PHP has a great reflection API, but as at least in the current PHP version (as far as I know) we only can get the PHPDoc as a string, without parse it. I need to get the parameters and the type of them with reflection. [...] But the type is different.

His script (based loosely on a bit of a component from the Zend Framework) parses the file and its comments and grabs the variable types from the PHPDoc blocks on each method and associates them.

If you're looking for a more mature solution than just this script, take a look at Docblox, a PHP 5.3 documentation generator.