If, for some reason, you need to change the default umask (022) in Mac OS X Leopard the following article helps you in achieving that goal.
The article refers to Leopard server.
I tried it on Leopard workstation and seems to work just fine too.
The same can be done for Mac OS X Tiger in Terminal
sudo defaults write -g NSUmask -int value
as stated in Command Line 10.4 2nd edition manual
The above example applies on Mac OS X Panther too.
*** BE CAREFUL ***
These changes could possibly have nasty consequences on the normal behaviour of the system.
