This appeared in the Microsoft Online Services Update email:
Enhanced Support for Mac OS
The October Service Update includes several enhancements that will provide a more
efficient communication and collaboration experience for organizations with Mac
users.
A new Sign-In Client for the Mac OS provides a single sign-in experience and auto-configuration
of Office for Mac applications and the Safari browser for use with Microsoft Online
Services.
Other Mac features in this Service Update include:
- Support for Entourage 2008 Exchange Web Services (EWS), including Global Address
List (GAL), Calendar Free/Busy Lookup, and Out-of-Office notifications
- Global Address List support for Entourage 2004 and 2008 when using the Sign-In
Client for Mac