First of all this is a bug in PHP/4.0RC1.

I wrote a very simple php "script" to look at the command
line args passed --  args.php.

#!/usr/local/bin/php -q
<?php
echo "$argc\n";
for ($i = 0; $i < $argc ; $i++) {
  echo "$i {$argv[$i]}\n";
}
?>

I then called :
> ./args.php "http://foo.com/one?bar=++10&baz=100"
4
0 ./args.php
1 http://foo.com/one?bar=
2 
3 10&baz=100


Notice that even though the arg is quoted,  the +'s seem
to split the single arg into 3.