D7 Theming: so awesome you'll need a change of pants

The changes to the Drupal 7 Theme layer aren’t revolutionary, but there are so many improvements, you may have trouble… ah… controlling yourself.

• Crappy-themes-be-gone™
• Template cleanup
• Numerous name changes (like sidebars and menus)
• phptemplate_ prefix is gone
• $classes and $classes_array
• theme functions and preprocess functions
• More regions, less hard-coded page variables
• Holy crap, content is now a block!
• template suggestion wildcard
• JQuery UI
• Granular theming
• html.tpl.php
• hook_page_alter()