Your application's PHP classes autoloading lives a the autoload.app.php file. All classes in PIMF are statically mapped. It's just a simple array of class to file path maps for ultra-fast file loading. Feel free to change the mappings and directories at autoload.app.php file.
Mappings from class names to file paths:
static $mappings = array(
'MyFirstBlog\\Controller\\Blog' => '/MyFirstBlog/Controller/Blog.php',
'MyFirstBlog\\DataMapper\\Entry' => '/MyFirstBlog/DataMapper/Entry.php',
'MyFirstBlog\\Model\\Entry' => '/MyFirstBlog/Model/Entry.php'
The core's PHP classes autoloading lives a the autoload.core.php file. Note: this file is autogenerated with PHPAB - please do not edit!!!