I've recently returned from an amazing time at Drupalcon Copenhagen, and wanted to highlight some of my favorite sessions, events, and departing thoughts (this also serves as preparation for the impossible task of summarizing such an epic and comprehensive conference in 15 minutes for this week's Portland Drupal group). While I can't cover them all, the complete list of videos from Drupalcon Copenhagen can be found here.
Jeremy Keith, not only touched on the core functionality and concepts of HTML 5, but also spent a great deal of time focusing on the history and reasoning behind the design.
This session sets a new bar for presentations, not just at Drupalcons, but for conference presentations in general. Amitai Burstein managed to map the complexities of international relations to the new flexibility of groups in Drupal 7, in a witty and hilarious manner.
UPDATE: Amitaibu has an alternate version of the presentation video that shows his introduction a bit better.
If you haven't been following the development of this Drupal mapping solution, this session is a good place to catch up. The presentation did an excellent job of detailing the creation of complex maps, that are based on views and are fully exportable.
Find out how using Drush make to build sites encourages developers to contribute back patches, rather than running monolithic and duplicative code repositories. Unfortunately, as of this writing, the video is not available on archive.org. Once it is, it is well worth a watch. In the meantime, Jeff Miccolis has this related blog post.
Angie Byron's session provides a nice, friendly overview of some of the major, user-facing changes that Drupal 7 will bring. For a more behind-the-scenes view, Damien Tournoud highlights some of the lesser-known features (video) such as job queues and the fine-grained caching options available. Larry Garfield covers some goals for Drupal 8 (but first, of course, let's get Drupal 7 done).
Speaking of which, the 2 code sprints (the first after the Core Developer Summit, the second after the conference), saw the critical issue queue drop to 13 at one point, but then, with the additional attention of developers, it bounced back up to around 25, and is currently hovering at 29. There's even a site to see what these numbers might mean for a release date for Drupal 7.