What are the changes to Drupal 7 Theming VS Drupal 6?

I've heard that Drupal 7 theming has been simplified, but couldn't find much resources on the internet about it.

I'm especially interested to learn what are the changes that boost productivity and efficiency for themers.

Since D7 is officially being launched, surely many more people will start asking this question too, so this is a good place to consolidate 开发者_如何学Cour knowledge of how to effectively and efficiently theme D7.

Thank you!

Some Drupal.org resources:

• http://drupal.org/update/theme/6/7 changes from Drupal 6 to Drupal 7 with regards to themes
• http://drupal.org/node/948216 some procedural notes on going about updating themes

The most thorough resource I've seen is PingVision's A peek at Drupal 7 theme system changes post.

You may also want to check out the Drupal 7 Theming - what's new presentation and the DrupalEasy podcast interview with John Albin Wilkins, author of the theming chapter in the Drupal 7 Module Development book.