[eluser]WanWizard[/eluser]
You're overloading the save() method of the Datamapper object. Not a problem, but take into account that the save method can have parameters, which you ignore here.
So if you do this, it won't work:
Code:
$county = new Country(1);
$city = new City();
$city->name = 'test';
// parameter is ignored by your model!
$city->save($country);;