Young Hanh (aka yhahn) gives some insight into some of the modules that have allowed Development Seed to customize the user experience of their Open Atrium Drupal distribution. At DrupalCon DC in 2009, Hahn predicted that exportable definitions would be the future of solving deployment problems, and went on from there to help develop the Features module. Over the past year, exportable definitions have played a huge part in fueling the rise of Drupal distributions. Context allows you to manage contextual conditions and reactions for different portions of your site. Spaces allow you to override the values of a Drupal object that would otherwise have a single, sitewide value. And Persistent URL (PURL) is an abstracted request handling API tool that allows you to pass URL arguments into different modules, which goes beyond the limitations of the existing core menu system.

Improving the request handling of Drupal core was one of the biggest architectural issues that was talked about amongst the Drupal developers during DrupalCon in looking forward to Drupal 8. You can find out more of their plans at the Butler group for the next steps for the and the initial request handling architecture brainstorming session.

Some other context-related modules mentioned are Panels, Panels everywhere, and the Display Suite.

For more information, check out Hahn's presentation called "The Heart of Open Atrium: Context, PURL and Spaces" as well as Jack Aponte's notes from the session.