My girlfriend turned up this morning with her scanner, a Trust Flat Scan USB 19200. Its an old model from around 5-6 years ago, and she'd lost the driver disk. This was clearly a challenge for Linux …
I plugged the thing in (its a USB scanner, which pulls all its power from the USB bus) and the light went on. However the scanner application which comes with both PCLinuxOS and Ubuntu wouldn't start up. Time for some investigation. I got a root terminal shell and tried poking around
lsusb showed that the scanner was recognised.