Idle postmasters....

  At any given time, I'm fairly likely to see one or more postmasters
which are sitting around, doing absolutely nothing.  They're not taking
any CPU time, nor *have* they taken even a second of the CPU.  They just
sit there, idle.  There may be up to six or seven of them.

   The machine is a quad Xeon, and the CPU usage rarely exceeds 30%.  It
hasn't touched swap in months, and has more than enough RAM, so they
processes don't seem to be waiting for CPU or I/O.  The PG version is
7.0.2.

  Any ideas what's going on?

steve