I have taken all my users off our Xserve and am having them lpr-print directly to the individual printers. As I can't think of any benefits to spooling through th server--apart from imposing user-specific page quotas--I think I'll leave it the way things are. I guess, I'll never find out, whether our problems were fixed by this OS update.
One particular problem I saw--and it was acknowledged by Apple support staff--was that my print queue wouldn't start properly upon server reboot. My workaround was to stop and then restart print services after each reboot.
Dominik Hoffmann