Matthew Yglesias is wondering about vampire-disposal techniques. Specifically, he's wondering if beheading works, or if the stake-in-the-heart is the only way to do it.
Well, really, there's no one way to do it. That is to say, within any one author's vampiric milieu, there's generally ways that work and ways that don't, but you won't find agreement across the board on this. With some authors, beheading works; with others, only the stake in the heart will do; with still others, burning is adequate. Most seem to accept that vampires cannot survive exposure to direct sunlight; many accept that vampires can be harmed -- caused great physical pain, if not outright killed -- by being forced into physical contact with holy objects. (In other words, touching one with a crucifix.)
Vampires, of course, are folkloric creatures, and folklore varies wildly from place to place, so you'd expect that the methods of killing them vary from place to place. However, assuming that beheading and the stake in the heart both work equally well for your particular vampire, there are reasons why staking is preferable that mainly have to do with the difficulty of severing a head from a human body.
No matter what we see in the movies, like at the end of Fellowship of the Ring when Aragorn manages to recover from getting his ass kicked by a giant orc with enough strength left over to lop off the beastie's head in a single stroke, it's much harder than that. Many beheadings were carried out less than successfully on the first attempt, and most famously, the executioner required three attempts to finish off Mary Queen of Scots. There's a reason why Dr. Guillotin's invention was so popular in France, after all; beheading is a non-trivial operation, and if you're attempting to kill a vampire, you want a method that has the best possible chance for success on the first try. Generally speaking, would-be vampire slayers whose first attempts fail don't get to move on to a second attempt.
Staking is a "higher percentage" procedure, since it's usually attempted during the day, so the vampire will be asleep and thus (a) unwilling to attack in broad daylight, and (b) confined to the coffin. Of course, staking is also a "Get it right the first time" affair; miss the heart or don't penetrate the chest bone, and you now have an awake and angry vampire coming at you. Staking is not easy.
Other stories have vampires being vulnerable to fire: if you can seal them up, you can them dispose of them by burning them. The problem here comes in sealing them up. Vampires, in many legends, have the ability to become non-corporeal, and thus they can escape from nearly any enclosure. (An episode of the original Star Trek, by the way, had fun with this very idea in positing a blood-consuming creature that was literally gaseous. The episode is called "Obsession", if you're interested.) This led to the creation of a pretty nifty means of vampire disposal: bottling.
What you did was tempt a vampire by putting blood in a bottle, so that when the vampire comes along, in order to drink the blood, he has to become non-corporeal and actually enter the bottle. Of course, he'll sense a trap, but the slayer will basically drive him on by brandishing crucifixes and crosses and spritz-bottles filled with holy water and the like, basically driving the vampire inside the bottle. Then, while he's inside the bottle drinking away (think of the Pepsi commercial when the kid sucked himself into his bottle of pop), the intrepid hunter corks the bottle. And to forestall any ability the vampire might have to "seep" through the cracks in the cork or wiggle out that way, the hero pastes a holy picture to the underside of the cork, thus driving the vampire backward. Then the hero simply tosses the bottle into a large bonfire. End of vampire.
Other methods are less reliable. If one fears that a recently deceased person might become a vampire, you could bury him face down, in hopes that he would dig downward, into the bowels of the Earth, as opposed to digging out and thus be able to terrorize the populace. Needless to say, this assumes a certain degree of stupidity on the part of the vampire that isn't really safe. The same idea applies to burying the dead at a crossroads, in hopes that the crossroads will confuse the vampire long enough that he'll still be standing there when the sun rises. Not particularly reliable either, that one.
Of course, one wonders why, if people were so afraid that corpses would turn vampiric, that they didn't simply stake every newly deceased person and be done with it. I assume there's some religious reason for this.
What I always wonder: do vampires have preferences for human blood? Is there such a thing as 'taste' where vampires are concerned? Would a vampire ever say anything like, "Man, that was a good one! He'd just taken his vitamins!"?