GenVibe - Community for Pontiac Vibe Enthusiasts

In my 2009 base Vibe: If I goose the accelerator a little bit, not too much, I hear a very brief high-pitched whistling type of sound...almost like a cricket chirp, but not quite as sharp and well-defined. Almost like two pieces of fast-spinning metal are barely coming into contact with each other for a half a second (not that that's what's happening, but that's sort of what it sounds like, it's hard to explain).

It's not loud or anything, but it's just audible enough and just long enough to be annoying, considering I slightly press the accelerator many times during any given drive. Anyone heard this noise before?

No, I have not noticed this. I hear a whistling at highway speeds if my window is not raised completely (wind noise) or I can bark a tire coming off line if I dip into the throttle too aggressively coming off line, but that's it.

I would try replacing the serpentine belt.
Use Continental Elite (formerly Gatorback).