The xD card in the camera was definitely corrupt - I don't know why. It wasn't possible to access it at all when it was in the camera, but in a card reader, trying to dd it gave I/O errors, but using photorec I managed to recover most of the photos. Photorec is by the same person whose TestDisk I used to sort out Dr K's corrupt NTFS partition.

After formatting the card it seemed to be OK again - I don't understand why there was a "hole" in it, so that it was impossible to dd beyond a certain point.

The photos are here.

See also:
http://freshmeat.net/projects/photorec/.