I'm trying to allow my "deploy" user to have access to files created by www-data:

• I added "deploy" to the www-data group.
• I set umask to 002.

When I run the following commands, I'm not seeing the result I expect:

deploy@ubuntu-lucid-32-generic:/var/www$ groups
www-data adm dialout cdrom plugdev lpadmin sambashare admin deploy sysadmin

deploy@ubuntu-lucid-32-generic:/var/www$ newgrp www-data

deploy@ubuntu-lucid-32-generic:/var/www$ umask
0002

deploy@ubuntu-lucid-32-generic:/var/www$ mkdir test

deploy@ubuntu-lucid-32-generic:/var/www$ ls -la test
total 0
drwxr-xr-x 1 deploy deploy  68 Nov  7 20:37 .
drwxr-xr-x 1 deploy deploy 476 Nov  7 20:37 ..

I see that:

• The folder doesn't belong to the www-data group.
• The folder permissions don't have group-write (775).

Note that the /var/www directory is owned by the deploy user:

drwxr-xr-x  1 deploy deploy   510 Nov  7 20:45 .

How can I give www-data selective access to directories? Or, how to share the /var/www directory with my deploy user: I don't care who owns it, as long as I can write to it, and so can www-data. (Ideally I would set up a directory with SGID access for www-data.)