Nope, this is not a new expression of the global positioning system (that I have now become totally reliant on) with an additional social layer. Rather it is a way of thinking about navigating the increasingly scattered content that once was enclaved on a single website, a way of thinking about the destination and the different (and increasing number of) ways of getting there.
Why positioning? From a consumer’s perspective, reminding me of why I am here, how I got here, got this far and what I need to do next is very helpful from a contextual point of view. Already proven to be useful on-site, this will become increasingly true as content that is currently found on those same sites is made available to the consumer, on demand, in different forms and via different channels. From a content owner’s point of view, a combination of both on and off-site web analytics tools can provide a good indication of the performance of your content both on-site and in the broader eco-system.
Why shared? Two reasons, one is that as consumers we inevitably fall into groups defined by demographics, psychographics or other behavioural identifiers and will tend to behave and track in certain particular patterns and as such follow a similar path (persona driven design and communication planning along with on and off-site behavioural targeting will allow you to map those macro journeys effectively). The other is simply another expression of the age old value exchange - As a site or content owner, I want you as a consumer to perform certain valuable actions, (sign up, opt in, buy, connect, friend, follow, link etc) and, since, you are here, one can imagine that these actions might be on your agenda too - assuming that the work I did to attract you here in the first place was correctly focused and that you are in the right place. As such, our Shared Positioning System (the navigation - from the initial interaction point to the conversion point) has one, and only one role - to enable both of us to get from point A to point B in the most effective way possible. All of the rest (page views, stickiness, etc...) is simply noise and must not detract us from the real focus of the journey; the destination.
All of this is contestable of course, but it is most beautifully testable and if you’re not testing it - why not?