files in directory inherit group permissions as well as ID

[GyroTech]

Hello all,
Is there a way for files in a directory to not only inherit the group ID 
(chmod g+s) but the group permissions too?? umask only seems to hold 
true on a per-user, per-session basis and affects all files created by 
that user. Is there a way for just these files in one directory to 
inherit the group id and group permissions of the directory regardless 
of user writing to it??

Thanks,

GT