Microsoft has finally posted a formal resolution to the problem caused by installing SP2 in your SharePoint Services (WSS) of Office Server (MOSS) farms. For those that missed the news a few weeks back, an SP2 upgrade causes the current license key to become inactive 180 days after the upgrade. If this happened, the environment would become unusable by users, indicating that your "trial" has expired. Many fixed the problem by simply re-entering their product key.
This fix that has been released can be applied either before or after the SP2 upgrade and will ensure this problem never occurs.
The 32-bit version can be downloaded here: http://download.microsoft.com/download/2/F/5/2F51AB71-1325-49D2-9CB9-18DEC4780E99/office2007-kb971620-fullfile-x86-glb.exe
The 64-bit version is here: http://download.microsoft.com/download/5/B/B/5BBD34A9-C528-42B0-8A5F-9A8997B25C32/office2007-kb971620-fullfile-x64-glb.exe
For more information, you can read the kb article here: http://support.microsoft.com/kb/971620