samba - Sep 2004 - hiding guests' workgroups from the browse tree

In my company there's no day without some external collaborator / friend 
plugging their client PC to the net.
I'd like the browsing of shares not showing their workgroup's names, is 
it possible ?
Since from a rapid research it seems is not possible in windows I 
suppose is either not directly possible with samba, what I'm asking for 
is some kind of hack (iptables rule ?) maybe someone is already using 
with success ...
(It's not a security concern, if the workgroups are still reachable 
knowing the path of the share i don't care, only I don't want to see :

-COMVERT
--public
--software
-HELL
-WORGROUP
--Shared Documents
-PORNBUS
--photo

it's annoying isn't it ?
)

-- 
Simone Cittadini
=================COMVERT S.R.L.
via F.lli Bressan, 21
20126 Milano - ITALY
Tel +39.02.27006796(aspetta un beep)103
simonec@comvert.com
http://www.comvert.com