discoloration which Apple has already addressed, the mooing sound (click to listen) seems to stem from the MacBook's fan repetitively turning on and off at certain temperatures and loads. Early reports from those who installed the update over at sister site TUAW, seem to suggest that this SMC update to 1.4f10 does the trick while also reducing the MacBook's overall temperature. So what's keepin' ya sport, best get a mooove on. Yeah, that was painful... but so there.
[Thanks to everyone who sent this in, via TUAW]