We’ve just released a small 4.2.1 update which fixes a couple minor issues reported after the 4.2 release. Namely:

• Added back Fetch & Retrieve as an optional plugin (with Support Center integration).
• Fixed an issue with using languages that used locales not enabled on the server. You can now use any language defined in Cerb4; and if PHP5 or your server OS doesn’t know how to format according to that locale it will default to English for timestamps, numbers, etc.
• Fixed an issue with Watchers suddenly receiving notifications for messages subsequently flagged by the parser as spam.
• Fixed an issue with the migration of Group filters on Workspaces.

You can find the full ChangeLog in the forums:
http://forum.cerb4.com/showthread.php?t=2071

The typical upgrade instructions apply:
http://wiki.cerb4.com/wiki/Upgrading_to_Newer_Versions_of_Cerberus_Helpdesk_4.0

Thanks!
-Jeff@WGM