dumb question: multiple postmasters on Solaris

Hi,

I believe this is a dumb question, and I have a sneaky feeling that I've
seen something about this on the list before, but I can't find it in the
archives.

I am used to using PostgreSQL on Linux, but we have moved some of our
work onto Solaris multiprocessor boxes. Now, I see multiple instances
of postmaster -i in the output from ps. Am I right in believing that
this is just an artifact of the way the OS deals with threads, or is
pg_ctl doing something evil and spawning extra back ends? I _think_ the
latter is impossible, because there's already one back end bound to the
port. But a little reassurance from someone experienced with Solaris
would sure make my day better!

Thanks,
A