You may want to download the standalone version of the Hosted Messaging and Collaboration 4.5 Help file.
HMC 4.5 brings together powerful Microsoft enterprise products such as Microsoft Exchange Server, Microsoft Windows SharePoint Services, and now gives you Microsoft Office Communications Server 2007, which manages all real-time communications such as instant messaging (IM) and audio and video conferencing.
Other new features and enhancements:
- Exchange Server 2007 SP1: Web-based OABs and resource mailboxes
- Windows SharePoint Services: multi-tenant People Picker functionality
- Provisioning capabilities have been expanded: Microsoft Provisioning System (MPS) cross data store integration procedures and Individual Information Worker (IIW) tenant model