When in vertex paint mode - the object being painted is displayed as shadeless. This makes painting on a complex model difficult - as you cannot really see what you are doing. You can use dirty vertex paint to make the geometry visible - but this is not ideal.
This is improved in the Blender render textured view using multitexture shading which gives you a shaded view.
In cycles the object remains shadeless in both shaded and textured mode.
Can this be shaded so it is not shadeless when using cycles?