There have been some recent discussions on Shared Memory problems
in Darwin on the darwin-kernel list at lists.apple.com.
The subject is : shm_open and mmap: Invalid argument?
Tain't clear to me if this is relevant to the MacOS X and
Postgresql shared memory problem that I see mentioned here
from time to time... ( some of the discussion centers on
releasing the segments).
Perhaps a more knowledgeable postgresql person should
take a look.
Jerry