Now, I do realise that Activity Streams is no perfect world out there. There is still plenty of room for growth in the areas of hitting the right context, collaborative / social filtering, awareness, full integration with business processes, pervasiveness and so forth. However, I still feel, very strongly, that Activity Streams will never become your next overloaded Inbox.
Activity Streams permeate throughout transparency and openness
They help you, greatly, be done with the obsession to read AND respond to everything
They facilitate serendipity and Informal Learning
They help flatten organisations and traditionally hierarchical structures
They inspire an open knowledge sharing culture
Mentions some interesting work from stream skeptics who claim our streams will become just as overcrowded as our inboxes.