You may probably know that starting with syslog-ng 3.0, we started poking into the message payload by being able to extract information from the log messages and use that information in structured form for message routing, filtering and storing them as separate fields in a database table.
You may have read about patterndb on this blog or on Marci's blog and we have also given talks about it on different conferences: NNM 2009 and LSM/RMLL 2009.
The reason I'm raising the topic here again is that we have now released about 8000 patterns covering about 200 applications for patterndb and are now in the process of creating a community site to maintain this database.
You can download the database from www.balabit.com.
Also an important thing to know that syslog-ng OSE 3.1 features enhanced performance with regard to handling information extracted from the message payload and it also has support for the latest patterndb database format. So if you want to try the new database, fetch a copy of the latest 3.1beta2 release.