This issue can be solved with 2 modules:
- Features - Allows you to export content-types, users and structures (e.g. Taxonomy, Image-styles, etc.) into a module-like package An excellent guide is available here: http://drupal.org/node/580026
- Feeds - Feeds is a contributed module that allows one to import and export content from a csv, xml, or rss format. Visit the feeds project page for more information.
- For "node-content" export/import use the "Node Export" module.
Future of Drupal Exportables
Drupal is well known for being modular and flexible. One of Drupal's strength is the move toward more and more exportable settings.
In fact, there currently is an initiative toward providing more of this exportable abilities: