Haystack looks interesting initially, particularly its use of RDF, but its UI simply tries too hard.  What is trying to hard?  Imagine what a Boeing 707 cockpit used to looks like before modernization.  That is trying too hard.  Not everyone is a control-freak with a need to see everything together.  Human mind is not capable of focusing on more than one thing effectively.  People don't need to see the contents of Inbox and News at the same time.  UI is not just about how one shows information, but also about when and how to hide information.  Haystack has a long way to go.