Whining

My girlfriends 99 4 runner makes a high pitch whining noise constantly, it sounds like the whine of an old domestic fuel pump. Its not the belt, nor the tranny becuase it make this noise at idle as well. It's not hurting performance or gas mileage but is rather annoying. The car runs and drives wonderfully though. Does this sound familiar to anyone, im not used to these engines, Any comments appreciated, Thanks

Do you just want to know if anyone has heard of it, or help diagnosing it?
If you want help, how about some details.

Is it constant or intermittent?
Does it vary with RPMs?
Do you hear it thru the stereo speakers?

I would like to attempt a fix. It is consistant, it is loudest at high rpms in every gear (its automatic) It doesnt come through the speakers.