samba - Jul 2008 - using UPN instead of samaccountname with winbind

Hello,

I have winbind authentication working my a win2003 AD, however, I have
to authenticate using DOMAIN+samaccountname right now.   I would
prefer to use the UPN.  The UPN in my case is their full email address
username@domain.com.   The context for this authentication could be
anything that pam supports. How can this be done?   I am using
samba-3.0.28 on Centos 5.

Thanks!
Terry