Dedicated flashguns are designed to work with a specific late model family of cameras. They have additional connectors to carry information back and forth between the camera's brain (CPU or Central Processing Unit) and the flash. Dedicated flash adjusts the strength of the flash when the camera aperture is changed.
Non dedicated guns generally have an Auto setting which means you set the aperture on the flash gun and have to match this with the aperture on the lens.
don't think it will TTL (ie you only get an auto flash), and of course, since the triggering voltage for the flash might be different for different manufacturers, you might either fry the flash, fry the camera, fry both, or it works beautifully.