Free, mobile and open, private and visual. These are the trends that are hot on the Web right now. Snapchat is the epitome of all these trends coming together. Its popularity may be a thing of the moment—as are the snaps it's based on—but it's rare to see a company position itself in line with major Internet trends in such an effective way.
Right place, right time. Everyone wants to share; they just want to do it with each other instead of telling the whole world about it. Talking direct is inherently social.