PostgreSQL and 2-node failover cluster solutions

Hi, we have 2 PostgreSQL servers running multiple instances and would like
to automate failover between them. We store db data on NFS storage on
dedicated Netapps. We can currently perform manual failover by dropping
the instance on one server and starting in on the other (the init scripts
handle bringing virtual IP up/down and the NFS volume is automounted as
needed).

My question to you: are there any simple, reliable and free cluster/fail-over
(whatever you'd like to call it) solutions that you know of to automate
the above? I'm prepared to give a bit on the simple and free if necessary,
although reliability is pretty important.

I have been looking at Kimberlite, but it doesn't look like it supports NFS
shared storage, only locally attached. Otherwise it is almost perfect.

Many other offerings floating around are either expensive commercial, or
overly complex requiring kernel patching and complicated setups.

Any suggestions appreciated. Especially if you've already solved this!

Regards,
Chris