"PHP 5.3":http://snaps.php.net/ will include "lambda functions and closures":http://wiki.php.net/rfc/closures.
One interesting thing that will come from this will be the ability to dynamically add a method onto a class at runtime, by combining lambas with the magic __call method..well, at least a hack to make something like this.

Effectively this is similar to "traits/grafts":http://wiki.php.net/rfc/horizontalreuse, except you don’t have to define anything in a new class, you just extend the object itself when you come to use it.
You could also use a singleton within the Extensible class that keeps track of any added methods and propagates them to any other existing or new instances.

<?php
class Extensible {
        var $_methods=array();
function __call($name, $args) {
if (array_key_exists($this->_methods, $name)) {
call_user_func_array(array($this, $name), $args);
} else {
throw new Exception(‘Unknown dynamic method ‘ . $name . ‘ called in class ‘ . get_class($this));
}
}

function __set($name, $value) {
if (is_callable($value)) {
$this->_methods[$name] = $value;
}
}
}
class MyClass extends Extensible {
function test() {
echo ‘Non-dynamic method’;
}
}

$object = new MyClass();
$object->test2 = function () {
echo ‘Dynamic method’;
};

// test() is defined within the static class definition
$object->test();
// test2() was created dynamically at runtime, but you call it just as
// if it had been in the class definition
$object->test2();
?>

EDIT:
Incidentally this my first proper post sent via email. w00t.