This will only fix the YLOD temporarily (few months). I advise anyone who is attempting the fix, to NOT proceed with the guide! If this is done more than once is could result in your pcb being "warped". The only way to truly/permanently repair your ylod, is to have it serviced by a 3rd party repair service team.
They use a reflow stations, ex: (Zephyrtronics ZT-7000) these are professional tools that are valued at thousands of dollars.
Ebay has these services readily available, generally in half the cost that sony would charge, but the best part is, you get your original ps3 back, not to mention you get a 3 month warranty for the service.
Also you do NOT receive a refurbished ps3 like sony does, so your data and psn downloads are all safe and sound. personally, I prefer using ebay for this service, as i find it very convenient to complete this repair process.
Although this topic/thread is a few months old now, be advised, that gilksy's method of the ylod fix involves using a heatgun in an attempt to reflow the bga's, ic's, and pcb.