Interesting terminology from some of the writers of Heroes on their efforts to spread out the narrative across different media to create a new meta-objective for their audience: The mystery of following the story across all media.
An attempt to adress the decreasing relevance of scheduled broadcast for the audience.
Henry Jenkins calls this transmedia storytelling and moderated the conversation with the Heroes writers (after a ridiculously long introducton from someone else).
The standard view of this kind of thing is that the alternate media maximise the commercial exploitation or exntends the lifetime of the main product, the series or films, but Jenkins seems to believe the balance is shifting so that the series really requires engaged multi-channel viewing.

Certainly explains my complete failure to appreciate why people watch Heroes.