I don't know if this is a bug or that session_register() just doesn't work the way I expect.  In a single script if I use session_register() then try to access $HTTP_SESSION_VARS["var"] I get a null entry.  I'd expect that as soon as I register a variable that I should be able to find it in the $HTTP_SESSION_VARS.

<?php
session_start()
$test = "this is a test";
session_register("test");
print $HTTP_SESSION_VARS["test"];
?>