Start evaluating Office Communications Server today. Office Communications Server 2007 R2 delivers streamlined communications for your users so they can find and communicate with the right person, right now, from the applications they use most (like Office Outlook).
Once installed, the OCS trial lasts for 60 days.
It is a multipart download that is rather large overall, but includes just about every piece imaginable of the OCS suite, pre-installed:
Windows 2008 Domain controller:
DC.part1.exe, DC.part2.rar, DC.part3.rar