I have the same problem with self compiled atmel-wlandriver 3.4.1.0
(http://atmelwlandriver.sourceforge.net/news.html) and a PCMCIA wireless Siemens
PC-Card 11.
When shutting down my notebook (Toshiba Satellite 2410) a message similar to the
one reported (nregister_netdevice: waiting for atml0 ...) is shown and there is
no way of cleanly shutdown the computer (I have to force disk sync and reboot
with ctrl+alt+sysrq+...).

If I disable the wireless interface (ifdown atml0) before rebooting or shutting
down there are no problems.

I'm using Hoary

uname -a returns:
Linux satellite 2.6.10-5-686 #1 Fri Jun 24 17:33:34 UTC 2005 i686 GNU/Linux

lspci returns :
0000:00:00.0 Host bridge: Intel Corp. 82845 845 (Brookdale) Chipset Host Bridge
(rev 04)
0000:00:01.0 PCI bridge: Intel Corp. 82845 845 (Brookdale) Chipset AGP Bridge
(rev 04)
0000:00:1d.0 USB Controller: Intel Corp. 82801CA/CAM USB (Hub #1) (rev 02)
0000:00:1d.1 USB Controller: Intel Corp. 82801CA/CAM USB (Hub #2) (rev 02)
0000:00:1e.0 PCI bridge: Intel Corp. 82801 PCI Bridge (rev 42)
0000:00:1f.0 ISA bridge: Intel Corp. 82801CAM ISA Bridge (LPC) (rev 02)
0000:00:1f.1 IDE interface: Intel Corp. 82801CAM IDE U100 (rev 02)
0000:00:1f.5 Multimedia audio controller: Intel Corp. 82801CA/CAM AC'97 Audio
Controller (rev 02)
0000:00:1f.6 Modem: Intel Corp. 82801CA/CAM AC'97 Modem Controller (rev 02)
0000:01:00.0 VGA compatible controller: nVidia Corporation NV17 [GeForce4 420
Go] (rev a3)
0000:02:07.0 FireWire (IEEE 1394): Texas Instruments TSB43AB22/A IEEE-1394a-2000
Controller (PHY/Link)
0000:02:08.0 Ethernet controller: Intel Corp. 82801CAM (ICH3) PRO/100 VE (LOM)
Ethernet Controller (rev 42)
0000:02:0b.0 CardBus bridge: Toshiba America Info Systems ToPIC95 PCI to Cardbus
Bridge with ZV Support (rev 32)
0000:02:0b.1 CardBus bridge: Toshiba America Info Systems ToPIC95 PCI to Cardbus
Bridge with ZV Support (rev 32)
0000:02:0d.0 System peripheral: Toshiba America Info Systems SD TypA Controller
(rev 03)

cardctl ident returns:
Socket 0:
  no product info available
Socket 1:
  product info: "IEEE 802.11b", "Wireless LAN Card S"
  manfid: 0x0000, 0x0000
  function: 6 (network)

lsmod returns:  (atmelwlan driver is pcmf504_2958)
Module                  Size  Used by
binfmt_misc            11496  1
ipv6                  257888  17
proc_intf               3908  0
cpufreq_userspace       4348  1
cpufreq_ondemand        6140  0
cpufreq_powersave       1632  0
af_packet              21992  2
pcmf504_2958          110676  1
pcmcia                 22244  5 pcmf504_2958
nfsd                  207232  8
exportfs                6080  1 nfsd
lockd                  63944  2 nfsd
sunrpc                149124  2 nfsd,lockd
video                  15972  0
sony_acpi               5928  0
pcc_acpi               11008  0
button                  6480  0
battery                 9988  0
container               4320  0
ac                      4676  0
yenta_socket           21344  1
pcmcia_core            57984  3 pcmf504_2958,pcmcia,yenta_socket
e100                   33920  0
mii                     4896  1 e100
ohci1394               34596  0
snd_intel8x0           32352  2
snd_ac97_codec         74144  1 snd_intel8x0
usbhid                 31936  0
uhci_hcd               32816  0
usbcore               119000  3 usbhid,uhci_hcd
pci_hotplug            33488  0
intel_agp              22140  1
floppy                 58864  0
rtc                    12472  0
pcspkr                  3496  0
md                     47440  0
dm_mod                 59420  1
capability              4648  0
commoncap               7712  1 capability
lirc_sir               15456  0
lirc_dev               13092  1 lirc_sir
snd_seq_midi            8512  0
snd_rawmidi            24480  1 snd_seq_midi
snd_seq_oss            34176  0
snd_seq_midi_event      7424  2 snd_seq_midi,snd_seq_oss
snd_seq                52528  6 snd_seq_midi,snd_seq_oss,snd_seq_midi_event
snd_seq_device          8460  4 snd_seq_midi,snd_rawmidi,snd_seq_oss,snd_seq
snd_pcm_oss            52132  0
snd_pcm                94696  3 snd_intel8x0,snd_ac97_codec,snd_pcm_oss
snd_timer              25060  2 snd_seq,snd_pcm
snd_page_alloc          9732  2 snd_intel8x0,snd_pcm
snd_mixer_oss          19680  2 snd_pcm_oss
snd                    55012  13
snd_intel8x0,snd_ac97_codec,snd_rawmidi,snd_seq_oss,snd_seq,snd_seq_device,snd_pcm_oss,snd_pcm,snd_timer,snd_mixer_oss
soundcore              10016  2 snd
toshiba_acpi            9068  0
speedstep_ich           5100  0
speedstep_lib           3940  1 speedstep_ich
freq_table              4004  1 speedstep_ich
nvidia               3923452  12
agpgart                33608  2 intel_agp,nvidia
sr_mod                 17188  0
sbp2                   23816  0
scsi_mod              127552  2 sr_mod,sbp2
ieee1394              108312  2 ohci1394,sbp2
tsdev                   7520  0
evdev                   9344  0
psmouse                21320  0
mousedev               11288  1
parport_pc             37252  1
lp                     11144  0
parport                36744  2 parport_pc,lp
ide_cd                 41700  0
cdrom                  40220  2 sr_mod,ide_cd
ext3                  137256  1
jbd                    60536  1 ext3
mbcache                 8356  1 ext3
ide_generic             1312  0
piix                   10340  1
ide_disk               20416  3
ide_core              129356  4 ide_cd,ide_generic,piix,ide_disk
unix                   28276  1057
thermal                13320  0
processor              22452  1 thermal
fan                     4388  0
fbcon                  37504  71
font                    8192  1 fbcon
bitblit                 5472  1 fbcon
vesafb                  6724  1
cfbcopyarea             3808  1 vesafb
cfbimgblt               2912  1 vesafb
cfbfillrect             3488  1 vesafb