I'm sorry - I think I misunderstand something here.

I have just tried with the example values in 
http://sourcefrog.net/projects/natsort/example-out.txt

Expected result: no change from the input array to the outputted array.
Actual result: the input array order is incorrect where values have a '0' in front of them

Sample code:
<?php
$arr=array(
  '1-2', '1-02', '1-20', '10-20',
  'fred', 'jane', 'pic01', 'pic2',
  'pic02', 'pic02a', 'pic3', 'pic4',
  'pic 4 else', 'pic 5', 'pic05', 'pic 5 ',
  'pic 5 something', 'pic 6', 'pic   7', 'pic100',
  'pic100a', 'pic120', 'pic121', 'pic02000',
  'tom', 'x2-g8', 'x2-y7', 'x2-y08',
  'x8-y8'
);
natsort($arr);
var_dump($arr);

note that the values in the array there are /already sorted/ according to natsort. With that in mind, the output should match the input.

Actual result:
array
  1 => string '1-02' (length=4)
  0 => string '1-2' (length=3)
  2 => string '1-20' (length=4)
  3 => string '10-20' (length=5)
  4 => string 'fred' (length=4)
  5 => string 'jane' (length=4)
  6 => string 'pic01' (length=5)
  8 => string 'pic02' (length=5)
  9 => string 'pic02a' (length=6)
  23 => string 'pic02000' (length=8)
  14 => string 'pic05' (length=5)
  7 => string 'pic2' (length=4)
  10 => string 'pic3' (length=4)
  11 => string 'pic4' (length=4)
  12 => string 'pic 4 else' (length=10)
  13 => string 'pic 5' (length=5)
  15 => string 'pic 5 ' (length=6)
  16 => string 'pic 5 something' (length=15)
  17 => string 'pic 6' (length=5)
  18 => string 'pic   7' (length=7)
  19 => string 'pic100' (length=6)
  20 => string 'pic100a' (length=7)
  21 => string 'pic120' (length=6)
  22 => string 'pic121' (length=6)
  24 => string 'tom' (length=3)
  25 => string 'x2-g8' (length=5)
  27 => string 'x2-y08' (length=6)
  26 => string 'x2-y7' (length=5)
  28 => string 'x8-y8' (length=5)

This should fix this one:

Index: strnatcmp.c
===================================================================
RCS file: /repository/php-src/ext/standard/strnatcmp.c,v
retrieving revision 1.10
diff -u -1 -r1.10 strnatcmp.c
--- strnatcmp.c	15 Jul 2004 01:26:03 -0000	1.10
+++ strnatcmp.c	7 May 2008 18:34:31 -0000
@@ -118,6 +118,6 @@
 		/* skip over leading spaces or zeros */
-		while (isspace((int)(unsigned char)ca))
+		while (isspace((int)(unsigned char)ca) || ca=='0')
 			ca = *++ap;
 
-		while (isspace((int)(unsigned char)cb))
+		while (isspace((int)(unsigned char)cb) || cb=='0')
 			cb = *++bp;

Rasmus, why don't you commit the patch if it fixes this..?

I was hoping for some feedback on the patch to hear if it actually fixes it.

Checking this further, this patch messes up the order of "0" in an array that contains negative values like "-123", so it still needs some work.

Bad result.

$a[0]=00001;
$a[1]=00008;
$a[2]=00005;
$a[3]=000011;
$a[4]=00003;
$a[5]=000014;
natsort($a);
print_r($a);

Array ( [1] => 0 [0] => 1 [4] => 3 [2] => 5 [3] => 9 [5] => 12 )

Excuseme bad example
the right one

$a[0]="00001";
$a[1]="00008";
$a[2]="00005";
$a[3]="000011";
$a[4]="00003";
$a[5]="000014";
natsort($a);
print_r($a); 

Array ( [0] => 00001 [3] => 000011 [5] => 000014 [4] => 00003 [2] => 00005 [1] => 00008 )

This bug has been fixed in CVS.

Snapshots of the sources are packaged every three hours; this change
will be in the next snapshot. You can grab the snapshot at
http://snaps.php.net/.
 
Thank you for the report, and for helping us make PHP better.

Fixed in CVS

This fails now (in both 32bit and 64bit systems):

# php -r '$a = array(.0001, .0021, -.01, -1, 0, .09, 2, -.9, 33); 
natcasesort($a); var_dump($a);'
array(9) {
  [2]=>
  float(-0.01)
  [7]=>
  float(-0.9)
  [3]=>
  int(-1)
  [4]=>
  int(0)
  [0]=>
  float(0.0001)
  [5]=>
  float(0.09)
  [1]=>
  float(0.0021)
  [6]=>
  int(2)
  [8]=>
  int(33)
}

Yeah, we talked about that on internals.  It's pretty much an either/or thing.  If you want numeric sorting, sort it numerically.  This is natcasesort and is more intended for filenames and such.  So this is expected.