Messenger for Mac 7 - available now
We have just launched Messenger for Mac 7, which allows Mac users to connect to Office Communications Server 2007 (or Live Messenger).
Built for corporate Mac users on Office Communications Server 2007, Messenger for Mac 7 gives co-workers new ways to communicate easily with each other in different locations or time zones. Additionally, personal users will find a few improvements for managing their contact lists.
Messenger for Mac includes support for IM, presence, voice and video.

Say it face-to-face with audio and video
If your company has Office Communications Server 2007 and Messenger for Mac 7 installed within your corporate network, you can participate in face-to-face meetings with co-workers in other cities, countries, or on Windows PCs using multi-party audio and video conferencing.

Take better advantage of your corporate network.
For corporate users, increased support for Office Communications Server 2007 makes it easy to search a corporate address book from within Messenger and quickly find internal contacts and their presence information. With corporate users each having an account on your corporate network, communications are more protected.

Let co-workers know you’re available to chat.
Thanks to Mac OS X Bonjour instant networking technology, people will be able to see if you’re on the local network. New “presence” enhancements in Messenger for Mac 7 include the ability to add a personal message to your contact information, so co-workers will know more about when you’re available to chat.
Get more information at http://www.microsoft.com/mac/products/messenger/default.mspx or download it from http://www.microsoft.com/mac/downloads.mspx?pid=Mactopia_Messenger&fid=20726b11-2ae8-4828-8b66-2964e277166d#viewer