I've recently posted a topic asking about CUPS & SAMBA printing.
I followed the tutorials described, and perhaps I've managed to do something, but I'm not sure.

My smb.conf (important parts):

[global]
workgroup = SRSP
realm = SRSP.DPF
server string = Samba File Server TESTFSV06
security = ADS
allow trusted domains = No
log level = 2
log file = /usr/local/samba/var/samba.log.testfsv06
socket options = TCP_NODELAY SO_RCVBUF=8192 SO_SNDBUF=8192
load printers = Yes
printcap name = cups
printing = cups
browseable = yes
dns proxy = No
idmap uid = 10000-60000
idmap gid = 10000-60000
template homedir = /home/%U
template shell = /bin/bash
winbind separator = +
winbind use default domain = Yes
hosts allow = 10.11.8.0/255.255.252.0

[printers]
comment = Impressoras em TESTFSV06
path = /var/spool/samba
browseable = no
public = yes
guest ok = yes
writable = no
printable = yes
printer admin = root

[HP1300Nuinf02]
comment = HP 1300n em TESTFSV06
path = /var/spool/samba
printer admin = root
browseable = yes
printable = yes
writable = no
guest ok = no
valid users = @g_nuinf

I'm using AD users (so g_nuinf is an AD group).
/var/spool/samba is chmoded 1777


My /etc/cups/printers.conf:

# Printer configuration file for CUPS v1.1.23
# Written by cupsd on Tue 04 Oct 2005 03:12:18 PM BRT
<DefaultPrinter HP1300Nuinf02>
Info HP 1300n Nuinf 02
Location STI - 10. andar
DeviceURI socket://10.11.10.31:9100
State Idle
Accepting Yes
JobSheets none none
QuotaPeriod 0
PageLimit 0
KLimit 0
# AllowUser @g_nuinf
</Printer>

I removed the "AllowUser" line (although it was working fine, following CUPS log).
SAMBA is compiled with CUPS support.

What is happening is:
If I try to print from a Windows client with my user (which belongs to group g_nuinf), the printer shows as "Access Denied", but when I try to print, IT PRINTS!!! But I receive no log of printing activity at SAMBA, only at CUPS.
And if I try to print from user "test" (with no permissions at all), it doesn't print, but then there is no log, neither at SAMBA or CUPS.

I'm positive I'm missing something, but what?

A correction: Printing is not working.
I tried with another user from g_nuinf and nothing happened (the same as user "test": no print and no log).
I tried my user again and couldn't print as well.

Maybe this can help:

I raised SAMBA log level from 2 to 3, and then, just by opening the "Printers" section at the Windows client (where I will receive the "Access denied. Unable to connect" message), SAMBA log goes crazy, and one thing I noticed was this:

[2005/10/07 17:09:05, 3] nsswitch/winbindd_user.c:winbindd_getpwuid(404)
[ 0]: getpwuid 11541
[2005/10/07 17:09:05, 3] nsswitch/winbindd_group.c:winbindd_getgrnam(216)
[ 0]: getgrnam g_nuinf
[2005/10/07 17:09:05, 3] lib/util_seaccess.c:se_access_check(250)
[2005/10/07 17:09:05, 3] lib/util_seaccess.c:se_access_check(251)
se_access_check: user sid is S-1-5-21-2694665981-1503952256-2714348651-24082
se_access_check: also S-1-5-21-2694665981-1503952256-2714348651-21001
se_access_check: also S-1-1-0
se_access_check: also S-1-5-2
se_access_check: also S-1-5-11
se_access_check: also S-1-5-21-1085031214-796845957-839522115-513
se_access_check: also S-1-5-32-544
se_access_check: also S-1-5-32-545
se_access_check: also S-1-5-21-1085031214-796845957-839522115-512
se_access_check: also S-1-5-21-1085031214-796845957-839522115-1109
se_access_check: also S-1-5-21-1085031214-796845957-839522115-2258
se_access_check: also S-1-5-21-1085031214-796845957-839522115-1687
se_access_check: also S-1-5-21-1085031214-796845957-839522115-2257
se_access_check: also S-1-5-21-1085031214-796845957-839522115-4258
[2005/10/07 17:09:05, 3] nsswitch/winbindd_user.c:winbindd_getpwuid(404)
[ 0]: getpwuid 11541
[2005/10/07 17:09:05, 3] rpc_server/srv_spoolss_nt.c:_spoolss_open_printer_ex(1747)
access DENIED for printer open
[2005/10/07 17:09:05, 3] rpc_server/srv_lsa_hnd.c:close_policy_hnd(200)
Closed policy
[2005/10/07 17:09:05, 3] rpc_server/srv_pipe_hnd.c:free_pipe_context(543)
free_pipe_context: destroying talloc pool of size 4938

Apparently it recognizes the group name, but somethings goes wrong when checking pwuid