Conversation starter : player character death

The A Perennial Favorite entry at Penny Arcade touches on the issue of player character (PC) death. It doesn't offer any real answers (aside from mind flayers), but is a great conversation starter, and it's a discussion that we have annually at PrinceCon. I'm one of those GM's who rarely kills players. I'm not against PC death, but I tend to run towards wanting to make the players feel as if they're in mortal peril and bringing their characters close to death without actually killing them. The problem, of course, is that over time players will get to feel "safe" because they know I'm not *really* going to kill them. Killing more characters seems like an easy solution, but even there I want to be careful to not kill PC's off randomly. After all, this isn't real life, it's a story we're telling in which the PC's are principals, so if there's going to be PC death, it should help to advance the story**, either as a tragic slaying at the hands of the Bad Guy, or as a heroic sacrifice.

** obviously, if the player is being a nitwit, their character can be killed at will. I'm assuming competent players without deathwishes.