As soon as the engine turns over a pretty loud, medium-pitch "clicking" noise is heard in the engine compartment. It repeats rapidly, and the rapidity increases as the gas pedal is depressed. It sounds in any gear, including park and neutral.

The noise is only evidence of a problem. The car still drives well, the engine is smooth, etc.

I'm taking her in to the dealer tomorrow am, but before I go... anyone have ideas or experience with this sound?