Hi
The User Principal Name (UPN) format isn't supported (except for EAP-TLS , within the certificate).
However, if you read the previous statement in
http://www.cisco.com/en/US/products/sw/secursw/ps5338/products_user_guide_chapter09186a0080193aba.html#222679
you can see that WinNT,Win2K and WinXP Dial Up Networking clients provide the domain name in a specific domain field and not necessary in the UPN format.
In Wireless Environments it depends on the authentication method :
EAP-TLS is covered for UPN format support.
LEAP (Cisco ACU) also asks for the domain in a seperate field
PEAP (either MS Client or Cisco client) also ask for the domain in a seperate field.
Hope this helps,
Ami