Well - I ported the spam package to OpenACS, but apart from making sure that all queries work under postgres and the switch to use acs-mail instead of acs-messaging (was that its name?) there was nothing that I changed. And I haven't touched it since the port.
Why there is almost the same set of scripts under www/ and under www/admin/ is still beyond my understanding.
There are a lot of possible improvements and cool things that a better spam package could do, and it's certainly better to start from scratch then trying to build from the existing spam package, since there isn't really much in it.
But until some people actually build a better package I would suggest to keep it in the distribution - at least for this release. It is at least a bit better then having nothing at all.