[wlug] v4l question - /dev/video0

Hi there, I'm trying to get a couple of webcams going in Linux. One is a firewire card and one is a USB. They are both loaded on my system and are partially usable (e.g. Firewire one works in Gnome Meeting). My question is how does /dev/video0 come into existence with video 4 linux (aka v4l)? I have tried using mknod and that can create it but it doesn't make it usable. I've hunted around the web heaps and not found much at all. Questions: - is there a magic step to create /dev/video0 automatically and I haven't set it up? - or is it that my drivers aren't really working well? Ian