I haven't done any serious WP development since version 2.8, although I fiddled a bit with version 3.0. Short of reading the release notes on each version, what are the major things to take note of as 1) a theme/plugin developer and 2) an administrator?
I've already identified three things:
- Custom Post Types and Taxonomies
- Custom Menus
- Post Formats (a la Tumbr)
What else do I need to take note of?