Thanks for the reply, sorry I didn't give enough details.
I think I set up motion properly: I have the three files as you stated, and both cams are *detected*. However, I have that in the log:
[2] Error starting stream VIDIOC_STREAMON: No space left on device
[2] ioctl (VIDIOCGCAP): Inappropriate ioctl for device
Despite the misleading title (there is space left on device!), it seems from what I found with Google that it means "not enough bandwidth". I can reproduce the exact same thing on my desktop computer: when both cams are plugged on the same USB controller, the error occurs; however if they are plugged on different controllers, it works fine.
As there is only one controller on the Sheeva, I cannot do the same.
When you had your two cameras running at the same time, was it on a Sheeva too?
TIA
greg
PS: cams are set up at 352x288 palette 0 (YUV)