Basic form of chromatic aberration could be achieved by using proper (colored) bokeh image with bokeh DoF feature. The aberation would then occur on the area of the image that is not in focus. Advanced form of computing chromatic aberration probably won't be available for a while, as Keymaster pointed out ;)
The main reason it's missing from all the render engines is simple fact that it's very easy to add and control as a postprocess effect, therefore rendering such an effect does not make a sense in the first place, unless it's above mentioned bokeh aberration
