Scalar type hints in upcoming PHP version?

Sebastian Bergmann writes that PHP 5.3.99 (which might be released as PHP 5.4) will introduce type hinting for scalar data types (e. g. function f(int $i, string $s) {}).

There is one thing to note: It seems like there are no plans to check or enforce the new type hints in the interpreter, so this feature might be purely syntactical. I am not sure whether this makes a lot of sense to me.