I have tested some cheap webcams with Raspi wheezy and vgrabbj.
The cameras are tested with my Ubuntu 12.04 servers and they are working there as expected.
In Raspi the pictures get dominoed. The 640x480 picture gets broken in 2-6 parts, which are placed randomly on the canvas. The hue/brightness/contras of the parts are random also.
I tried to turbo my Raspi, but it didn't help.
MemTotal: 237868 kB
MemFree: 186136 kB
Is it possible, that Raspi is, for some reason, too slow to process the data coming from the USB-camera ?