the applications layer

My "psionic" review of the recent film, "The Social Network":

As I understand it, Facebook exploits semi-open information in a
semi-centralized way.  Instead of the Applications layer being
something that people can really socialize about, it only supports a
closed, firm-like, collaboration at that layer.  I hope that Diaspora*
et al. will support "social apps" that aren't just miniature corporate
themeparks, but which instead correspond to real "grassroots social
organizing".  How might that work?

Some analogies:  this might be like adding a "problems" layer on top
of PlanetMath's mathematics encyclopedia, or like adding a radio drama
layer on top of the collection of sounds at Freesound.org, or like
adding a literary discussion layer on top of the collection of public
domain texts at Project Gutenberg.

Indeed, maybe these aren't just analogies, but could themselves become
"applications".