Can anyone explain how you can get a SIGPWR signal on a Solaris 10 local zone, but none of the other zones on the frame had a problem. 
Thats a strange one Jerry, never experienced that before.
Heres a stab but I am in no way 100% certain that the following is the case.
It could be that a momentary power drop was experienced as the global zone was monitoring that particular local zone via sched / zoneadmd but power restored before any other zones were effected including the global zone.
A sigpwr was then issued to init within the mentioned local zone which then executed the powerfail directive located in /etc/inittab.
Like I said just my two pence worth... 
Cheers,
SRG