Is it possible to to provide a link to view the full content of a post from teaser view with Fancybox? This is a handy feature with the Highslide module: http://drupal.org/project/highslide, in that you can define a div in the full post and preview that div by calling it from the URL, so that the desired divs are opened in a modal box but they aren't printed in the teaser view. The URL can be constructed as follows:

http://example.com/node/123#highslidepreview