I should perhaps have left out the subheading the New Yorker gave the piece, because it does Gladwell's argument a disservice. His point was that the kind of networks that social media makes easy do not always translate well to the organisation, discipline and strategy necessary for significant social activism.
Bear in mind that the piece was published before the Arab Spring bubbled up. Media reports exaggerated the roles that Twitter played in earlier demonstrations in Iran and Moldova. Gladwell: "Where activists were once defined by their causes, they are now defined by their tools."
I thought it was appropriate because it chimed with Dave Winer's idea that at some point, physical action has to replace virtual. Gladwell compares social media activism with the carefully planned civil rights protests in the 1960s: sit-ins, marches etc. Any sustained, significant physical action, he says, requires organisation.
I'm not saying Gladwell's argument has not suffered from the events of the Arab Spring. I still think, however, that his piece makes interesting accompanying reading, which is why I linked to it.