Domains of Dread are mentioned in MotP and there is IIRC some more mention of them in Open Grave. There aren't any codified rules like the old 2e Ravenloft setting provided, yet. As I understand it the boxed Gloomwrought and Beyond set will have something very similar though (coming in May). Basically the Shadowfell in a sense IS the Domains of Dread plus some.
MotP does have some basic rules for spelljamming. I'd say the way to work it in 4e would be to assume that you would be traversing the Astral Sea in your spelljammer. The various specific rules dealing with crystal spheres and whatnot don't exist, but you could easily reintroduce that stuff.
Planescape was a bit more dependent on the details of the Great Wheel, but MotP and DMG2 have a good bit of info on Sigil. You could certainly adapt most of the old stuff to the new cosmology, it has plenty of room for all the older stuff in it. Or just use 4e rules with the old cosmology, it will work perfectly well and the newer material should fit in easily.
Overall 4e is quite flexible that way, it really has little or no mechanics that rely on any specific cosmology.