On FC4, I have a Polaroid DC700, which works flawlessly as a serial device, under gtkam. I found a USB cable for it, and gtkam "says" it supports it under USB. But, there is NO communication happening. Here's what I get from an lsusb when I plug it in:
Bus 003 Device 001: ID 0000:0000
Bus 002 Device 019: ID 0784:2620 Vivitar, Inc.
Bus 002 Device 001: ID 0000:0000
Bus 001 Device 001: ID 0000:0000

That Vivitar line is the camera

and here's a tail of /var/log/messages
Jul 30 09:29:29 raymondjones kernel: usb 2-2: new full speed USB device using ohci_hcd and address 19
It would _seem_ to be IN there, but, nothing happens.
Anyone?

What happens when you try and mount it?

As root: mount /dev/sda1 /mnt/camera (it could be sda2 or sda3 or something too, and the directory you mount it on must exist)

On FC4, there's a thing called "udev", that controls what's really IN the /dev directory. I do not have any sd*, sg*, etc entries.