I have two USB webcams, why two ? becuase the first one was win98 ONLY :(

Kensington SVGA 67016 [0x47d/0x5003] (and I think I flashed its bios a while ago in win98)
Nisis DV1 [0x8ca/0x103] (has some non-webcam functionality as well)

The Kensington should be claimed by SE401 but I can not find this in my kernel modules and when I attempted to compile direct from the 
authors source code got lots of nasty errors :(

The ONLY Nisis driver I could find is stv680 which is in my standard modules but does not claim the device.

I unpacked the kernel sources and then used the make file from the se401 archive i got from the author deleted the se401.c and se401.h 
and copied the same files from /usr/src/ and ran make, insmod the new module and cat /var/log/messages clear shows it recognises the 
camera, not to get gqcam to test it.

hmmm, gqcam opens and appears to be seeing the camera just not picture, I tried to stop start from the menu but it crashed and i had to 
reboot just to get the camera to be recognised again :(
tying xawtv, same shows empty screen and on shutting and restarting get errors device in use :(
cat /var/log/messages also gives the same error, usb_control/bulk_msg: timeout
Looks like i need another reboot :(
The devices were not even getting power !(

Well I hacked the stv680 source (changed the device/manufacture id) and it accepts the camera connecting but then nothing can use it, 
worth a try!
Next I will dismantle the DV1 and see if the chipset is named!

Sent the chip names and numbers to the author of the STV680 drive who replied quickly and told me it was based on the SPCA504A 
chipset and that freshmeat had a linux project looking at these webcams, go the latest source compiled but then got linking errors when 
insmod'ing it ;( (I will have to contact their authors, but it explicitly states this is a development driver only so I do not hold out much 
hope).