The database version (db_version in wp_option) is 7558.
Changes in Minimum Requirements
- PHP 4.3 or greater (old requirement was PHP 4.2 or greater).
New User Features
- Administration Panels redesign (see WordPress Interface Guidelines)
- Widget-based dashboard
- You should be able to have any number of any widgets
- Search for both posts and pages (#1435)
- Use $wpdb->prepare everywhere
- Switch to expect unescaped data for internal functions
- XML-RPC refactor
- Plugabble media buttons
- Shortcode API