pfSense

Growl no longer uses UDP 9887 to send notifications as of 1.2.1 (as far as I can tell). Free versions 1.2.2-1.3 and paid version 2.0 and beyond support a more robust, 2 way capable, notification protocol GNTP which utilizes TCP port 23503:

http://growl.info/documentation/developer/gntp.php

I understand that PFSense is implementing PHP-Growl and most likely not maintaining the package but I thought I would list this here in an effort to garner some focus/attention to either upgrading PHP-Growl to support GNTP or adding/implementing a different package that supports GNTP such as: Python GNTP library:

http://pythonhosted.org/gntp/
https://github.com/kfdm/gntp

I have contact the owner of PHP-Growl to see if he had time or was interested in upgrading his plugin and will update this ticket as I hear back. Alternatively, on the off chance someone is interested in updating/forking PHP-Growl:
https://github.com/tylerhall/php-growl/

Although, it seems to make more sense to utilized the python GNTP library as the work already appears to be done, a web front end would be all that would be needed to be created.