Microsoft released an Office 2004 for Mac update today: Microsoft Office 2004 for Mac 11.2.3 Update. The key changes are: Spotlight support for Entourage 2004, Sync Services integration for Entourage 2004, and enhanced Smart Card support for Entourage 2004.
You can also find an update for MSN Messenger 5.1. This is mostly aimed at enterprise users using Microsoft Live Communications Server.
Big hurrahs all around on this one. While I've still got to play around with it at work tomorrow, one thing that I have noted is that the Sync Services appears to be a bit hit-and-miss. My Contacts have been synced correctly from Address Book but it doesn't seem to be syncing my iCal entries. Spotlight, however, seems to work great so I'm pretty happy about this.