This guide will help you retreive the qc-usb drivers for your Quickcam.
1) First, add this line to your /etc/pacman.conf. This will enable another trusted repository that contains the quickcam drivers.
[staging] Server = ftp://ftp.archlinux.org/tur/staging
2) Download and install the driver with:
pacman -S qc-usb24
pacman -S qc-usb26
If you use an alternate kernel (an older one, or an mm series) you can build the module with the PKGBUILD located here.
3) The module is called quickcam
NOTE: If you have Logitech Quickcam Messenger webcam, you need the qc-usb-messenger package from, for example, the AUR.