Rael Dornfest defines remixing (in the broader sense) as an "inherently more conversational" version of hacking:

Both are a feat of combinatorics, requiring decent
source, inspiration, skill, trial and error,
determination, and a goodly helping of magic.

Another interesting webcast from ETech 2005: Matt Biddulph, Paul Hammond, Tom Coates, and Matt Webb on Reinventing Radio, on the relathionships between broadcasting media and social software.

Also: Tim O'Reilly on The new architecture of partecipation. The image below is taken from this article: