Currently if you want to have raytraced reflections/refractions or use shaders other than the fluid shader you must convert the fluid to poly. It also helps to do a smooth on the result, but note that the animation and quality of the surface may not be as good as with the native fluid render.
If you are using a heightfield (pond) style fluid then the above also holds true, although instead of converting to poly one might consider using an ocean with a fluid wake or a fluid texture displacement instead of a pond fluid. The ocean numFrequencies can be set to zero so that one only sees the fluid wake texture.
Duncan