$ php -v
PHP 5.3.2-1ubuntu4.5 with Suhosin-Patch (cli) (built: Sep 17 2010 13:41:55)
Copyright (c) 1997-2009 The PHP Group
Zend Engine v2.3.0, Copyright (c) 1998-2010 Zend Technologies

$ php -i | grep json
json
json support => enabled
json version => 1.2.1

$ php json_test.php
INPUT:
[1,2,3]
OUTPUT:
array(3) {
  [0]=>
  int(1)
  [1]=>
  int(2)
  [2]=>
  int(3)
}

INPUT:
{"one":1,"two":2,"three":3}
OUTPUT:
object(stdClass)#1 (3) {
  ["one"]=>
  int(1)
  ["two"]=>
  int(2)
  ["three"]=>
  int(3)
}

INPUT:
"1"
OUTPUT:
string(1) "1"

INPUT:
1
OUTPUT:
int(1)