WordPress 3.0 introduces several new features including standalone or multisite installation options, custom post types, a new default theme called TwentyTen, child themes, and a theme menu builder. It also provides more installation control, bulk updates, custom taxonomies, and better post revision management. When upgrading, users are advised to backup their database and files, test the upgrade if possible, and check for PHP and MySQL compatibility. Security improvements include disallowing the default admin user, adding a security key, login lockdown options, and changing passwords regularly. The new default TwentyTen theme is built-in along with a theme finder. Additional theme features include new page templates and hooks for developers. Popular theme frameworks include Thesis

1. WordPress 3.0What’s next for the most popular CMS on the planet?1

2. highlightsWordPress 3.0 is in Beta(but not for long)

3. Stand alone or Multisite (formerly WordPress MU)

4. Custom Post Types

5. New Default Theme (YAY!)

6. Child Themes

7. Theme Menu Builder2

8. highlightsMore Installation Control

9. Bulk updates (themes/plugins)

10. Custom Taxonomies

11. Better post revision management (be careful here)

12. Everything is subject to change3

13. upgradeBackup database first

14. Backup disk files

15. If you can, test first

16. Should be backwards compatible

17. Validations to check PHP and MySQL4

18. securityNo Admin User