I only caught part of the talk because I had to keep so many aliens in check onboard our space station
However, the concept seems interesting: Instead of working with (the bugs of) a program, users complete tasks. On the desktop you see objects and tasks, or objects and connections to other objects. So the user gets a good overview of how things/objects/people interact.
You can even share your desktop/workspace! And I think this is best thing about it: to be able to take this "semantic thing" to the collaborative level. After all, people want to connect and share ideas; making this possible in an easier fashion is good.
On the other hand, it will require a little bit re-training yourself if you are - like me -used to working with programs. I will give DeepaMehta a spin, but I don't think I'll switch completely yet. The visual appeal is not there yet.
It also reminded me of mozilla's ubiquity thing, which I also will try out soon; a friend has been using it for some time and is very happy about it, limited as it is.