The key to this reboot is the understanding that page rank, and the fundamental search methodology of people looking for information, is about to be flipped on its head to a new model where the information is provided gestures of intention that allow it to target the user.
In my words - "You don't find the information, the information finds you". The difference between 'subscription' and 'attention' is the difference between boolean logic and fuzzy logic - one is a discrete 'subscribed or not subscribed' the other is a summarization over many events that signify interest in a subject or topic. Basically, pub/sub on acid. (You heard it here first...)
This is also interesting, in an 'opportunity' sense (emphasis added):
Gestures that span multiple engines and transports (AIM, GTalk, Skype IM, and Yahoo; Bloglines, Rojo, MyYahoo, Google Reader, Vista; the coming round of calendar gadgets; etc.) will inherently become more trustworthy as signals of interest than gamed links, walled garden cross and up-sells, and attempts at supplying authoritative information from incumbent publishers who can't or won't intermingle content from their competitors.