According to the Great Wheel cosmology presented in the 3e Manual of the Planes, the Astral, Etherial, and Shadow planes are accessable from all planes. If you take a look at the sidebars discussing the colors of color pools and etherial curtains, you will see that in both planes they have colors for the elemental, energy, and outer planes, thus implying their connectivity if they do not state it outright in some other place. I don't like this, as it differs too much from the 1e version, so I changed it back to the way it should be.
