WordPress 2.5 RC2 has been released yesterday. It is the prior version of the final WordPress 2.5. Matt, the WordPress founder, recorded a screencast to demo the new features.
The most significant changes of version 2.5 is on the admin panel. The layout has been redesigned and use a lot of AJAX for faster response, and it is cleaner now.
The “Write Post” page has been polished a lot. WordPress 2.5 now use Flash uploader and support galleries. Matt done his gallery page using WordPress 2.5. It looks great!
Most WordPress themes that work on WordPress 2.3 will work fine on version 2.5, because there are not many changes on the theme core. WordPRess plugin that work with the admin panel may require updates though.
Please keep in mind that WordPress 2.5 RC2 is NOT the final version. It may still contain bugs to be fixed in the final version. However, if you interested to try, you can download RC2 now (backup! backup!).