A common way to set up a directory for file sharing within a group, is:
$ mkdir foo
$ chgrp felles foo
$ chmod g+ws foo
$ setfacl -m group:felles:rwx foo
$ setfacl -dm group:felles:rwx foo
This ensures that any files created in foo is readable and writable by the group felles:
$ umask
0022
$ echo hi > foo/bar
$ ls -l foo
total 4
-rw-rw-r--+ 1 bhm felles 3 2010-09-23 00:18 bar
However, if you copy a file into foo, the default ACLs are not applied:
$ echo you > baz
$ cp baz foo/
$ ls -l foo
total 8
-rw-rw-r--+ 1 bhm felles 3 2010-09-23 00:18 bar
-rw-r--r--+ 1 bhm felles 4 2010-09-23 00:19 baz
$ getfacl foo/baz
# file: foo/baz
# owner: bhm
# group: felles
user::rw-
group::rwx #effective:r--
group:felles:rwx #effective:r--
mask::r--
other::r--
Why does this happen, and is there a way around it?
(Moving a file into the directory does not respect either ACLs or group ownership, but I can understand why: you might not want the permissions of a file to change simply because you change its name.)