best spam filter port(s) for postfix?

[Pollywog]

On Monday 01 October 2007 22:18:00 Chuck Swiger wrote:
> On Oct 1, 2007, at 6:54 PM, Philip Hallstrom wrote:
> >> By far the best anti-spam tool I've used with Postfix is policyd-
> >> weight.
> >> mail/postfix-policyd-weight
> >
> > Agreed. +1. Me too.
>
> Seconded (or thirded :).
>
> policyd-weight is much smaller than amavisd-new or SpamAssassin (it
> tends to run a couple of ~7 MB RSIZE processes, rather than a bunch
> of 45 - 80MB RSIZE), and it's caching of RBL/DNSBL lookups means it
> can handle and offload a bunch of queries that the others would do.

I didn't know about this one.  Is the installation and use documented 
somewhere?  (In case I can't find anything on Google).