scaling beyond 4 processors

Hello everyone!

Since our current Postgres server, a quad Xeon system, finally can't keep up with our
load anymore we're ready to take the next step.

So the question is: Has anyone experiences with running Postgres on systems with
more than 4 processors in a production environment? Which systems and
architectures are you using (e.g. IBM xseries, IBM pseries, HP Proliant, Sun Fire, 8-
way Opteron)? How about conflicts between Postgres' shared memory approach and
the NUMA architecture of most multi-processor machines?

Maybe it's time to switch to Oracle or DB2, but before I give up on Postgres, I wanted
to hear some other opinions.

Thanks for any hints and suggestions.

Best regards,
Stephan Vogler
CipSoft GmbH