Longhorn is a fine name, and it doesn't matter if somebody else used it 20+ years ago

I agree. You have to be a certain age to remember that a big part of Microsoft "Longhorn" was WinFS (Windows File System), which was intended to completely rework storage into a relational file system (or object-oriented depending on your view). "Longhorn" was supposed to do away with NTFS and failed miserably at that objective. I believe that WinFS delayed things considerably and eventually didn't ship with Vista.

Microsoft Longhorn's failure to be the next big thing was largely due to the bad implementation of a storage subsystem. The result was Windows Vista, which was derided as a bad OS (at least until Windows 8). Due to that history, I would not name any file system 'Longhorn'. It may not be the same as naming a cruise ship 'Titanic', but you wouldn't name it 'Iceberg' either.

I did this was going to be about the Vista and how some of the FS stuff that got cut was prescient. "This old thing that didn't work was ahead of its' time" is a whole genre of post (ex. Itanium)

Could've been worse eg Cairo or Blackcomb.

I remembered the Windows Vista reference as soon as I saw the name. That said, I don't think it's a big deal.

Indeed, does it uses .NET in its implementation, or are they already rewriting it into COM?