look at iTunes (Score 1)

I think this handles what we need, and can be implemented on current OSs.

In iTunes you don't manage the files. You manage metadata about the files. You can group songs arbitrarily (playlists), and each song can be in many groups. There's one pane where you see all the songs, so you can sort and find them without having to remember where you put them.

Now imagine it isn't just files, but each email message you get can have associated metadata and be placed into groups along with regular data files.

Then all you need is better search than iTunes, and maybe a more scalable way of dealing with the groups.

This is far better than Gelernter's approach because it gives you the ability to sort everything by time, but also to group in meaningful ways that aren't exclusive.

The other thing you need is that when you select a file, all the options for applications to open it should be easy. 80s tech associated a file with one application, but we're a bit more advanced and primitive than that. I might want to open an html file in one of several editors or word processors, and one of several browsers. I could want to open a Perl script in several editors, view the text in a browser, or execute the script.

Interestingly, you could make this compatible with current operating systems by creating directories for the groupings and putting links to the actual files in the directories. The way to hack namespaces is to put each actual file in a directory named for the id of the file. That way, for example, when you create or open a file in Photoshop, you get to name it something meaningful, but the gui replaces the file with a link, and puts the original in a uniquely-named directory somewhere behind the scenes.