i am checking out the new maya2012 fluids updates. the self attraction feature is good for pushing water over the edge.
in case of waterfall, it works, but it need a lots fine tuning and lots of work to optimize, because its really slow. its hard get air pressure behavior or a king of drag just with the velocity friction.
i think the particle based setup with secondary fluids support works best for waterfall. much better control and faster simulation.
anyway, interesting result.