YLOD, despite its full name, is the standard green LED, that goes yellow a single time for a split second, then flashes red (and that's probably just a "bug" in the animation, as yellow is red+green)when I restarted the system after it failed to load, I noticed my ps3 showed a yellow ligth for a few seconds Is this the infamous YLOD?
Webman, if you use it, blinks yellow while it loads itself or mounts games
You can use the PS3MAPI page to set the LED to whatever you want