As far as I know, there is no such thing as \'heaven\' in Planeshift. And, the Death Realm is far from \'Hell\'.
(Blurbing on in response to Zanzibar\'s post)
I think that permanent death and non-permanent death is explained in a few ways...
Those who can find themselves out of the Death Realm get a second chance at life. Those who cannot, in essence, \'die\'.
Now, how does this relate to our characters in Planeshift? Our characters are different than the common rabble, for lack of a better term.
If you are not some sort of warrior or mage, you would be at least a skilled crafter of some sort. And because of that, by offering a precious magical item or some-sort, or having some endurance and determination, players will be able to escape the death realm, with varying difficulty.