Beneath the faux Egyptian columns of the Muvico 24 multiplex at Arundel Mills mall, a handful of strangers edges toward each other, like secret agents at a blind meet. Which is sort of what they are, dispatched here to perform a task they neither initiate nor understand, and then move on. They call themselves flash-mobbers, and everywhere I traveled this summer, the news was catching up with this faddish expression of the latest technology...