To have group permissions set to read/write by default in Snow Leopard and Leopard, I used
/etc/launchd-user.conf to set the umask to 002.
This still works in Lion in every app except the Finder. Actually, Lion's Finder does apply the umask when setting permissions, but if the group (or everyone) bit is set to zero, the Finder will treat it like it's a 2, which makes new folders' group permissions read only.
Out of curiosity, I did try using the old technique I used in OS X 10.4, using the
defaults command to set the umask and NSUmask, but that doesn't work (which was expected).
I'm hoping to find a solution without having to use ACLs.
Does anyone know of another way to get the Finder in Lion to set group permissions to read/write by default?