Think they are talking NTFS Alternate Data Streams (Score 2, Interesting)

Well, it sounds more like Microsoft was intending to patent the "Alternate Data Stream" feature of the NTFS file system. You know, the whole a file called filename.txt:stream.txt is not the same as filename.txt:hidden.txt thing. Also, it's really nice that you can't see the newly created Alternate Data Stream (ADS) files. So using ADS it's a really nice way to hide stuff... even when running applications they will not show up as being a ADS executable (i.e. the executable will not be something like filename.txt and not filename.txt:foo.exe).

An example is shown here HOWTO: Use NTFS Alternate Data Streams

I'm not sure if a similar feature existed in prior OS or not, since I'm not familiar with the mainframe OSs of long ago, but, I think this feature has been a part of the NTFS file system since NT 3.1

Of course, the whole NTFS Alternate Data Stream (ADS) thing can be evil if it is misused. I mean you cant see ADS using DIR or Windows Explorer.