Alastair also poses the question:
"Will communities be the dictators of content in the future?"and he asks if these communities could gatekeeper the outcome by this collective endorsement.
I'd like to take this idea a little further and state that I don't believe it will be entire communities that will control this sentiment all the time and that key influencers within these communities will often lead the collective embrace (or attack).
However, unlike the concept of The Tipping Point, where these are super-influencial social magnets.... these people could be normal, everyday people. The downside is that it therefore makes it far harder to understand the dynamics involved and plan your influencing strategy accordingly.