I too am linking up power sources with planes in my campaign world.
It goes:
Sorcery - unsupervised divine/arcane power from slain god that the devils used to serve. I got rid of the distinction between the arcane and divine power sources, instead making it the same magic used differently. Divine magic is for social and cultural concerns, while wizardry is largely for construction and destruction. Clerics and wizards are both understood as "magi" in the setting. This is to encourage lots of different faiths and wizard traditions
Psionics - I'm planning to make the Astral Sea a conduit to the Far Realm. Thus, my astral sea will be a lot more like the Plane of Dreams than an outer space for the outer planes. This land of dreams will lend itself well to the psionics rules when they come out due to its specialization in enchantment and mind over matter magics. I will be restricting psionics to certain races with natural psychic abilities (githyanki for example) but will allow madmen to use psionics of other races if they come up with a wilder class.
Feywild - Druidic powers, will be represented by Fey Pact warlocks or modified wizards until I get something better (or learn enough of the system to build my own). I'm definately of the idea that shapechanging should be for a barbarian-like class while druids should be divine controllers. In fact, I'm content to leave shapechanging as an ability that druids, barbarians, and beastmasters could aquire as they wanted. In other words, they should be using per day ability slots.
Shadowfell - Necromancy of course, when we get a Necromancer class.
The Nine Hells - Infernal Pact Warlocks who can't or won't master sorcery. Summoners would be a variant of wizards initially, but gradually turn more and more to their summoned devils for power.
I'm not going to have an Abyss, I figure that the Far Realm is good enough for a "want to warp/unmake creation" enemy, so I'm going to transfer demons to be manifestations of evil, sort of like the furies of Greek mythology. Instead of being avengers however, they will be a festering wound stirring the same passions and crimes that created them. So Graz'zat would probably arise as a malevolent presence of lust and decadence in a corrupt noble court, Pazazu would arise as a Kenku clan leader guilty of a life of assassination and murder, while Lolth was created by the drow's treachery. I would prefer to use the Binder class to exploit the Demons, but I will probably use Warlocks in the short term.
The Far Realm - Star Pact Warlocks and Summoners - apocolyptic cults serve/want to wake Cthulu. Self-explanatory really. The Githyanki will also have learned to master this form of magic from the latent energies of the far realm within the Astral Sea.
