Based on a couple of comments to my Olive Oil Pumpkin Bread column yesterday, I'm wondering when it's really necessary to preheat an oven.
On the one hand, I can't imagine producing a flaky pie crust without that initial burst of high heat. On the other hand, when I asked my food folks on twitter whether they preheat, someone pointed out Joel Robuchon's Roast Chicken recipe, which starts in a cold oven and is apparently spectacular. (It's worth noting, though, that everyone else who responded weighed in heavily in favor of preheating, whether or not it lands us all underwater in a few years.)
What about you? Do you preheat when roasting? When baking? If you've produced gorgeously caramelized roasts, flaky pastries, or even a decent batch of cupcakes without preheating your oven, I'd love to hear about it.