This is interesting, however I feel like it has the same problem as Jef Raskin's ideas, namely that it does not scale well for tasks that are not text-based or personal organization/communication based (like mail or calendar management).

The thing I need most is a robust tag-based file system, that would let me have the same file in multiple places, and also would be intelligent enough to suggest tags for me.

That, and unlimited undo, everywhere, forever.