Here's an easy way to figure out exactly what version of LCS or OCS you have installed.

For LCS or OCS, check the following key:
HKLM\Software\Microsoft\Real-Time Communications\{92AC8981-AAD9-4391-8563-92E558EEF4C6}

For OCS 2007 R2, check the following key:
HKLM\Software\Microsoft\Real-Time Communications\{A593FD00-64F1-4288-A6F4-E699ED9DCA35}

Possible Values:

Server
SE - Standard Edition
EE - Enterprise Edition

Type
Volume - Volume License Edition
Eval - Evaluation Edition
MSDN - MSDN Edition

Version
2.0.5369.0 - Live Communications Server 2005 RTM
2.0.5470.0 - Live Communications Server 2005 SP1
3.0.6362.0 - Office Communications Server 2007 RTM
3.5.6907.0 - Office Communications Server 2007 R2 RTM