Selective sharing is set up through the card settings section of the Eye-Fi Manager, and allows all data to be backed up, with only specific data sent to a sharing service such as Flickr, Picasa, Smugmug, Facebook and YouTube. Selection is done on the camera itself, by simply using the Lock or Protect feature as a method of marking the images and videos you want to share.

More details on selective sharing can be found on the Eye-Fi blog.