They don't appear to be able to dream in the same way us people who see can.
http://vision.about.com/od/severevis...linddreams.htm

But it can be argued that these images are constructs based on input from other senses (and on what the dreamer has been told by the sighted about what these objects look like).
This most likely applies to blind people ingesting hallucinogens as well. There doesn't actually have to be stimuli from the eyes for 'images' to form. Even people who can see may experience synesthesia from hallucinogens, smelling colors, seeing sound etc. I would bet the blind experience more tactile and auditory effects as well.

Found one study on blind monkeys
http://www.hallucinogens.com/medsci/blindmonkeys.html