You're creating a reference to the variable that exists only in the function scope.

Same thing in PHP 5.1.6 (from the official ubuntu repositories).

I thought about the problem and considered the fact that a local 
variable vanishes when the function is done... so I tried the same 
with a static variable.. but it didn't work either:

<?php
function some_function(&$foo)
{
	static $_foo = NULL;

	if (is_null($_foo)) {
		$_foo = 1;
	}

	var_dump($_foo);
	$foo =& $_foo;
	var_dump($foo);
}

function some_other_function(&$foo)
{
	$foo = 2;
}

function yet_another_function(&$foo)
{
	$_foo = 3;
	$foo =& $_foo;
	var_dump($foo);
}

some_function($bar);
var_dump($bar);

some_other_function($bar);
var_dump($bar);

yet_another_function($bar);
var_dump($bar);
?>

Expected:
---------

int(1)
int(1)
int(1)
int(2)
int(3)
int(3)

Actual Result:
--------------

int(1)
int(1)
NULL
int(2)
int(3)
int(2)