The existing website import/export does not work... at least not as expected. A feature like that would be very useful for creating new sites from a "site template", reusing complete or partial page structures, transfer changes between two copies of the same site etc.
Remi Muller has provided more details about this here: http://developer.dynamicweb-cms.com/forum.aspx?ThreadID=31481
Also read the discussion about the current version here: http://developer.dynamicweb-cms.com/forum/cms-standard-features/websites-full-export.aspx
/Morten