nieronet: Just received confirmation that Windows Server 2012 Essentials is indeed supported for 12.1.2. I'll update the KB.
Edit: I did confirm that all four editions of Windows Server 2012 are supported with 12.1.2; in reviewing the KB document, however, I found the following notice at the very top:
Unless otherwise specified, all updates, editions, and Service Packs (SPs) for a listed Windows version are supported, e.g. Windows 7 = Windows 7 Home Premium, Professional, and Ultimate editions, all SPs. As Microsoft releases new Service Packs for Windows, these requirements may need to be re-evaluated--the newest Service Pack may require an updated version of the Symantec Product.
I have bolded the "all updates, editions, and Service Packs (SPs) for a listed Windows version are supported" portion of the document to make it stand out a little more. (This statement does not appear in the release notes version of the System Requirements, unfortunately).
I hope this helps alleviate confusion.
sandra