On a machine with lots of memory, I've run into pathological behaviour
with both the RHEL 5 and Ubuntu 10.04 kernels where the kswapd starts
eating up CPU and swap io like mad, while doing essentially nothing.
Setting swappiness to 0 delayed this behaviour but did not stop it.
Given that I'm on a machine with 128G ram, I just put "/sbin/swapoff
-a" in /etc/rc.local and viola, problem solved.

I've tried running without swap and the problem is if you actually do run out of memory then the process killer can take out your postgresql.

Sim