The RTM version of Exchange 2007 SP1 is build 08.01.0240.006, which is also represented as Version 8.1 (Build 240.6). This version information is consistently displayed in the Exchange Management Console, the Exchange Management Shell, and in the About Exchange Server 2007 Help dialog box. However, after applying SP1 to an Edge Transport server running the RTM version of Exchange 2007, the version information for the Edge Transport server will not be updated in the Exchange Management Console unless the Edge Transport server is re-subscribed to the Active Directory site. This is because the Edge Transport server does not directly update Active Directory with any configuration information. Instead, the version information for Edge Transport servers is recorded in Active Directory during the creation of an Edge Subscription. You can also determine the installed version of Exchange 2007 by examining the value for each installed role in the Registry at:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Exchange\v8.0\<Role>\ConfiguredVersion

ConfiguredVersion is a string value in the format of X.X.XXX.X (e.g., 8.1.240.6). 8 is the major version number. The .1 portion indicates it is SP1 (RTM would have .0). 240 is the build number, and the .0 after 240 would be .6, the minor build number. The value of the ExchangeVersion property remains unchanged in Exchange 2007 SP1; the output of the Get-ExchangeServer cmdlet for the ExchangeVersion parameter is 0.1 (8.0.535.0).  More info Click here