Webcam support in Linux still is in a quite premature stage of development. Applications like GAIM and other IM applications (except for aMSN) still lack in any form of webcam support.

Recently I got a new Cisco webcam and I started the challenge of getting it to work on my openSUSE 10.1 system. After figuring out which driver fits my Cisco VT II webcam (Logitech OEM) I was finally able to get some things working.

It takes a shipload of packages and kernelmodules to add USB webcam support on a Linux system. These are the modules and applications that worked for me:

modules:
modprobe v4l1_compat
modprobe videodev
modprobe v4l2_common
uvcview.ko

applications:
LUCview
Camelot
gqcam
aMSN

Here's a good matrix on webcam/driver support on Linux: http://mxhaard.free.fr/spca5xx.html

The UVC driver for Logitech cams is available from:
http://linux-uvc.berlios.de/