I am experiencing the exact same problem with the front cam.

'philnz' did you manage to make any progress on the issue??

My case is that the ribbon connecting the sliding parts broke, and after replacing this one part, which includes the front cam and light sensor, I can no longer use the front cam. Skype automatically closes when activating that cam, and also the /dev/video1 file is missing. I do have the /dev/video0 in place and can use normally the rear cam. When using the 'mirror' application it directly shows the rear cam.

After creating video1 as previously indicated, 'mirror' throws the message "Error: Could not open resource for reading and writing" and black screen. After restarting the N900, video1 is gone and 'mirror' shows the rear camera again...

Have absolutely no clue what is going on... how to know if it is a hardware issue??