(e) Logging pilot-in-command flight time. (1) A sport, recreational, private, commercial, or airline transport pilot may log pilot in command flight time for flights-
(i) When the pilot is the sole manipulator of the controls of an aircraft for which the pilot is rated, or has sport pilot privileges for that category and class of aircraft, if the aircraft class rating is appropriate;"
This section sounds to me that a first officer at a 121 airline with the appropriate type rating can log PIC for the legs he flew. I have always understood that only the person that signed for the aircraft (captain) could log it as PIC. If this is the case I suppose I could have gotten a job in Asia a long time ago.