A friends 3GS made hard contact with concrete and the screen shattered.
The repair guide was fairly complete, some comments for improvement: You mention the removal of a single screw on the inside (holding the LCD panel to the plastic carrier) twice. There is only one such single screw.
The hardest part of the repair is the removal of all the shattered glass in areas of the phone where the underlying adhesive is holding them. The digitizer does a good job of retaining the glass elsewhere.
The scariest part of the repair is the actual initial digitizer/glass/carrier assembly removal since pulling on shattered glass while holding the phone does not seem safe. It worked though. Just be patient, persistent, and keep wriggling the suction cup until the RTV or whatever Apple used to seal the screen assembly into the phone body lets go.
Please also add the following in the guide:
All adhesives holding the previous glass assembly should be removed from the plastic carrier part, using a spudger, the enclosed tweezers, etc. The reason being that the glass particles that may remain stuck on said adhesive (invisible to the eye but there) can create very concentrated areas of pressure, causing the new screen to crack. Clearing the track around the perimeter of the glass is important for the same reason.
The guide does not mention the removal of the plastic films covering the underside of the glass/digitizer before re-assembly either. I worry that someone might forget to do that.
Lastly, you might consider enclosing an alcohol wipe in case someone touches the lcd screen or the bare display assembly on the inside prior to re-assembly. The alcohol wipe would remove the traces of the fingerprint. Mentioning to folk that touching the LCD / exposed digitizer screen is a bad idea would probably also help.
Lastly, users should beware of the many tiny pieces of glass that may become airborne as they work to remove broken glass from the plastic carrier. Not only can the glass pieces fly far (due to their low mass + air flow from heat gun) but they are sharp and can hence easily penetrate skin.