Will the new iPrint 1.1 client for Macintosh provide secure printing
(authentication) to a 6.5Sp3/OES server or do I need to apply the
OESSp1/6.5sp4 update to the iPrint server as well?

I've installed the 1.1 client and was able to add a secure printer under
10.4. When I print, I get prompted to authenticate, that works, but the job
shows a status of "printing" forever and nothing prints.

My windows systems have no issues printing to the same printer via the same
user as on the Mac.