They say that they want to use it to discover more about how people search, share and edit information, and how they organise their search results. You can move around your search results, delete stuff, make notes and make it all visible to your friend, and also recommending sites to them. I like the idea of sharing my search results with people, because I often do a search for someone and then send them the best results for their information need, so this would just make it much easier. They also offer the possibility of mixing up photos or images with video footage results, and I can see that happening quite easily.
Read Write Web have a good post about U Rank and notice that you can't move results from the second page to the first page - I think this is a pretty big problem. The dragging and dropping doesn't work so well either they noticed.
You have to have a LIVE account to use it.