Some great new LCS 2005 sample code has been released recently to cover some commonly-requested messaging scenarios:
Role Agent for Microsoft Office Live Communications Server 2005
Role Agent is a sample Microsoft Windows service application that implements a role-based messaging agent for managing sessions and for brokering and dispatching instant messages between users and members of a defined group.
Group Alerts Sample for Microsoft Office Live Communications Server 2005
The group alerts sample application provides a simple user interface for sending instant messages to the online members of an Active Directory group or distribution list and its subgroups.
[Via The Goldfish Bowl]