WereWP

Starkers HTML5 « Nathan Staines
A great example of the implementation of html5 in a WordPress theme. It is a good place to start learning!
(tags: wordpress html5 starkers theme development)

Common Mistakes In Themes | scribu
Scribu gives us some useful things to keep in mind when developing WordPress themes. Some things may no always seem necessary for your theme to work, but they are widely used in plugins and should definitely be included in your theme.

Enhance Your WordPress Post Thumbnails in 5 Minutes Using CSS – woorkup.com
Another tutorial about the_post_thumbnail, the new WordPress function introduced with WP 2.9. This time, Jason Schuller shows us how to give a bit of eye candy to these thumbnails!

Which Template File does WordPress Use to Render Different Pages? | Digging into WordPress
An interesting and useful update of the template file hierarchy! Make sure you bookmark it!