Just today, I noticed that my S2000 is making this odd noise, almost like a very high-frequency vibration when I rev up the engine and then let go of the gas. Even when stopped, if I tap the throttle, it'll rev up, then make the noise as soon as I let go of the gas.

The noise is kind of like what you'd hear when you're dragging a desk w/ metal-tipped legs across a tile floor. Anybody have this problem? Hopefully it's a one-day thing (doubt it) and it'll be gone tomorrow...

Hopefully Honda will do something about it under warranty if it's still there in the morning....

 

I have had problems with vibrations under the circumstances you posted. Do you have a test pipe? If you do it is most likely your 02 sensor working itself loose and jiggling around in its bung (happened to me) or if you have a cat on your car still it could be the heat shield vibrating. Or if you have a aftermarket exhaust it could be your tips (my invidia tip on the left vibrates)

Jack up the car and listen for it.

 

I have no upgrades... The car is bone stock.

On a side note, the noise isn't back this morning. But we'll have to see how it acts after I actually drive it for a while.

Better keep my fingers crossed. =X