One of the most interesting new features of Drupal 7 is the improved and extended Render API.
In old times, page callbacks, blocks and other page elements returned simple HTML strings, which were then assembled into the final page structure at the theming level. In Drupal 7, instead, the page output is assembled out of renderable arrays.
In this session, I will first introduce the concept of renderable arrays and give an overview how they are used in Drupal 7 and how they differ from Form API arrays in Drupal 6. I will discuss the numerous advantages renderable arrays offer.
I will introduce some of the advanced features of renderable arrays and how they can be used to build a sane and alterable page structure.
Altering the final page output is a new concept in Drupal 7 which is a highly useful tool especially for custom site building and all these small last-second changes your client wants to be done on various elements coming from existing modules.
The Render API in Drupal 7 also introduces the concept of render caching which allows to cache the rendered output of resource intensive page elements.
Video at archive.org.
Site builders and module developers looking into using Drupal 7 effectively. Basic PHP and Drupal knowledge is assumed. Everyone who is interested in developing modules for Drupal 7 and not yet highly familiar with the Render API can profit from the session.