IMC, death is permanent for most characters, barring exceptional circumstances. I think that allowing Raise Dead, Resurrection, and True Resurrection to be thrown around willy-nilly cheapens the game and the believability of the world. In fact, I won't play in a game that ALWAYS allows PCs to return from the dead- thats just plain silly. Death has to mean something for it to have any meaning, and the way core D&D is set up, its merely an inconvenience.
As a rule, the PCs in my game are pretty careful- PC death is a rare event. The PCs don't charge into a fight without doing recon first, and if they are ambushed, they take a defensive posture. They always fight using a buddy system, to insure they increase their survivability. In 13 years of running my world, there have been 4 PC deaths, and only one of them came back. It was a druid who was grappled by a demon and fell into a column of black flame that was a gate to another sub-dimension. His body was incinerated, and the other PCs couldn't recover him, but his death sealed the gate for various complicated reasons. About 15 adventures later, the PCs found themselves trapped in the sub-dimension where that gate lead to (although they didn't know it at the time), and came across the PC, intact and healthy, but living a feral existance with only vague ideas of his former life. The party rescued him and brought him back to the real world, but the player who lost the character originally didn't want to play him again although he was tempted- he thought Menegar had recieved a second chance from his god, and took up guardianship of a sacred natural henge near a town where he ministers to the needs of the people (and is married to the best pie cook in town!). The player always has the option of bringing him back into play, but I doubt he will.
Every time a PC death has occurred in my game, its been a memorable and emotional experience. The death of the druid Menegar left everyone shocked, saddened, and looking at the game differently. The bard composed a ballad to his memory which became quite popular, and his druidic order made him the equivalent of a saint. The player didn't feel cheated or upset about the death, in fact he was rather proud of it, and still talks about it to this day.