I find it surprising that people are still debating this when there is a consensus view among the aviation press, the FAA spokespersons (spokespeople?!), and every FSDO rep I've seen quoted.

* You can log PIC as Safety Pilot, if:

1. A safety pilot is required by the regulations, and:
2. You are acting as the legal PIC, responsible for the safe outcome of the flight, during that portion of time when the 'Sole Manipulator' PIC is, er, solely manipulating the controls in simulated instrument flight*.

* You can log SIC (And only SIC) as Safety Pilot, if:

1. A safety pilot is required by the regulations, and:
2. You are not acting as the legal PIC, responsible for the safe outcome of the flight.

As to the initial question, I do not know the answer, but somebody did, and posted it. But as to this followup about logging PIC versus SIC for safety pilot time-- this is something we all should know and agree upon. All I'm doing here is re-stating what several others have said and trying to make it as clear as possible.
(But then, that's probably the goal of those who wrote the regs in the first place, and look where that got us..)

-Fox
*- Obviously, who is "legally" PIC needs to be agreed upon beforehand, and has oodles of considerations- Insurance, legal liability, responsibility.. and in the event of an accident, violation or incident, the FAA may decide that the person asleep in the back seat was the real PIC, so all bets are off. But as far as logging time, it's pretty straightforward: If you agreed before the flight that you were responsible for its safe outcome, then you may log PIC. If you did not, then you should (And are authorized to by the regulations above to) log SIC.