In the end I consulting the VirtueMart 1.1 Developer Manual and chapter 2.3.3: Other important Environment variables (*link at bottom)

Here it defines: Array $auth All the user information in one Array, always available in the global $_SESSION array.
and in particular: $auth["shopper_group_discount"]

From this we can construct the php code:

<?php echo ($auth["shopper_group_discount"]); ?>

and use it in one or some of the virtuemart php files, also we could use php to perform operations using ($auth["shopper_group_discount"]) :

<?php
if (($auth["shopper_group_discount"]) == ’00.00′) {
?> <p>You do not recieve discount</p> <?php }

else {
?> <p>You recieve <?php echo ($auth["shopper_group_discount"]); ?> % discount</p> <?php } ?>

Using this code (in \modules\mod_virtuemart\mod_virtuemart.php) around “// Show the Account Maintenance Link”
as we only wanted to show discount to logged in shoppers.

Hope it helps fellow coders out there.

*current link to the VirtueMart 1.1 Developer Manual: http://downloads.joomlacode.org/docmanfileversion/2/6/6/26645/VirtueMart_1.1_Developer_Manual.pdf

Similar/more info on it posted in Forum:
http://forum.virtuemart.net/index.php?topic=94797