Here is a very simple Powershell script that I put together to workout the current build/patch level of MOSS 2007.

I make no warranties etc about the quality of the code but it works quite well. Feel free to use and modify as you see fit.

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#
#    Author: Aaron Saikovski - Aaron.Saikovski@microsoft.com
#    Version: 1.0 - Built using CTP V2 build of powershell
#    Date: 25th Sept 2008
#    Description: Returns the current build version of MOSS 2007 you are running - Runs locally only. Obtains the version of MOSS 2007 from the local registry
#    Usage: Get-MOSS2007-Version.ps1
#
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cls
set-location HKLM:
$a = get-itemproperty -path "\Software\Microsoft\shared tools\web server extensions\12.0" -name Version
Write-Host "MOSS 2007 Version: " $a -foregroundcolor white -backgroundcolor blue
$Input = Read-Host "Press any key to continue"
set-location c:\