title: How does the DropBox Mac client work?
body: <p>I've been looking at the  <a href="http://www.getdropbox.com/install?os=mac" rel="noreferrer">DropBox</a> Mac client and I'm currently researching implementing a similar interface for a different service. </p>
  
  <p>How exactly do they interface with finder like this? I highly doubt these objects represented in the folder are actual documents downloaded on every load? They must dynamically download as they are needed. So how can you display these items in finder without having actual file system objects? </p>
  
  <p><strong>Does anyone know how this is achieved in Mac OS X?</strong> </p>
  
  <p>Or any pointer's to Apple API's or other open source projects that have a similar integration with finder? </p>