Microsoft has released Microsoft Messenger for Mac 7 which Microsoft claims “is an integrated communications client that enables you to communicate with contacts within and outside your organization.”
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 7 is a Universal application.
More info and download link (21MB) here.