I have the solution for this, but since it is problem that has occurred on two versions of Ubuntu I thought I'd share it.
Sometimes my integrated webcam is not functioning, I try to load cheese or skype and they tell me that no device is available.
I run dmesg and get:
dmesg | grep video
[ 0.326451] pci 0000:01:00.0: Boot video device
[ 20.999208] [Firmware Bug]: Duplicate ACPI video bus devices for the same VGA controller, please try module parameter "video.allow_duplicates=1"if the current driver doesn't work.
[ 21.608294] Linux video capture interface: v2.00
[ 21.610059] uvcvideo: Found UVC 1.00 device Laptop Integrated Webcam (05a9:2640)
[ 21.612608] uvcvideo: UVC non compliance - GET_DEF(PROBE) not supported. Enabling workaround.
[ 21.612692] uvcvideo: Failed to query (129) UVC probe control : -32 (exp. 26).
[ 21.612696] uvcvideo: Failed to initialize the device (-5).
[ 21.613004] usbcore: registered new interface driver uvcvideo