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?
In no particular order, other notable things are:
old default theme was deprecated in favor of annual theme changes, you jumped over Twenty Ten theme and current one is Twenty Eleven
WordPress MU was merged into mainline WordPress and is now called multisite feature
serious improvements to complex querying by taxonomies and custom fields
server requirements had been bumped to newer versions of PHP and MySQL
There had also been a lot of work done on admin UI and such. Too much of smaller stuff to list, just go through version pages in Codex (click version numbers, changelog pages are useless).