>To take another example, WAV MP3 OGG etc... All audio formats. All could
>have a common interface, so any program could read from and write to these
>files seamlessly, and the handler would handle the
>compression/decompression.

I dont think this really needs to be an OS feature but it might be nice if any applications that come with ReactOS offered sort of plug in file formats. You could easily write say an MSPaint clone that used COM objects to access image files. 3rd parties would then be able to write their own COM object for their own proprietary format. As good as this would be I dont think it needs integrating with the kernel but it should maybe something to bear in mind when people start to write applications to be shipped with ReactOS.