Moshe Weitzman on Page Rendering in Drupal 7
Moshe Weitzman talks about the new Page rendering flow and hook_page_alter() functionality in Drupal 7, which allows a more control over what appears on each page load. This will enable one-off customizations to the page loads in a much easier way. He talks about how Drupal 7 themes can now implement alter hooks, and how the page render arrays use the same approach as forms and nodes. Weitzman suggest that if you're new to the concept of render arrays to check out either the Pro Drupal Development book or some of the other training resources such as a workshop or other training videos.