One thing I like about development, is that sometimes, if something doesn't work as expected, you can create your own solution.
As we're still having spam problems, I've downloaded, installed and looked into the Community Server 2007 SDK, and here's an initial version of "Kartones.NET spam addon". You can download it from the Downloads section.
I've developed an (easy) rule to count post length and score spam points if a minimum length is not achieved.
It is quite easy to develop CS2007 modules, and it integrates perfectly with the default rules.
Note: The rule only applies to unregistered/anonymous users.