title: Developing "File Systems" for linux, mac, windows
body: <p>What technologies do applications such as dropbox (http://www.dropbox.com/) and expandrive (http://www.expandrive.com/mac) use to build functionality right into the local filesystems on each platform?  Can anyone suggest anything that would allow for maximum code reuse on all of the major platforms?</p>
  
  <p>I've only looked into FUSE on linux so far and I like what I see.  </p>