The system works but the frame rate is very poor: about 1 frame every 5 seconds. For my application I would preffer something towards 5 - 15 fps.
It must be something related to the configuration, driver or kernel USB related issue. I have a guruplug running Zoneminder with 3 ipcams and capturing in motion mode 3 fps/5fps when alarmed from each one (could be faster, but I prefer this configuration). The CPU load is really low (
http://dl.dropbox.com/u/14178571/Zoneminder/htop.jpg).
Where do you have the OS installed?. Maybe you could fine tune your system.
PacoLM