gistfile1.php

<?php
//module.config.php
return array(
    'factories' => array(
        'model.Foo' => 'Foo\Factory\ModelFactory'
    )
);

// Foo/Factory/ModelFactory.php

namespace Foo\Factory;

use Zend\ServiceManager\FactoryInterface;
use Zend\ServiceManager\ServiceLocatorInterface;

ModelFactory extends FactoryInterface
{
    public function createService(ServiceLocatorInterface $locator, $name)
    {
        // $name == 'model.Foo';
    }
}