My YLOD experience is this.
I was playing MW2 online and my PS3 shut down out of nowhere after I apparently got a message from somebody, it beeped and blinked the red lights until I hit the power button. Hit the power button and the PS3 stopped blinking with a solid red standby light. Powered on again thinking it was a fluke and it ran for like 10 minutes before it shut down again like it got kicked in the nuts. Tried to cycle it on again and this time it beeped at me, the green lit briefly, then the yellow/amber of the red/green lighting at the same time and then red blinky lights.
Basically it's down to an overheating issue, solder joints cracking and thermal paste evaporating. It's fixable permanantly with a reball of the chips with lead solder and better thermal paste supposedly with temporary reflow fixes available to hold you over in the meantime. I'm going to try and get my 60 gig fixed but I'm not sure how I want to do it just yet.