I have come to the conclusion that I can't keep up with SpamAssassin! The updates, requiring Perl updates, requiring dependencies which require further dependencies...
I was Googling around, and found Google Message Filtering. For $3 a year per user, they will filter out all spam and viruses for you, and send it on to your mailserver.
So far I am testing with just 6 users ( I have a total of about 60, so $180 a year will cover me) and we are catching lots of spam that SA was missing. The nice part is if you want, you can give each user their own login to the Postini interface (Google bought Postini and uses the technology for GMF) where they can review messages that were rejected. Users can also make their own filter tougher or softer depending on their likes.
For those interested, take a look:
http://www.postinidirect.com/news_event ... 020508.php
I plan to write a larger review at my blog.