Matt Mullenweg has announced the release of WordPress 2.8, available for download from wordpress.org as always, but also in your up to date WordPress install by automatic update. If you haven’t followed the beta talk, you’ll note that it is visually the same as the previous version, but a lot faster thanks to code improvement. It also featured a new widget interface that greatly improves the usage, as well as giving themes the same update and install treatment as plugins. Speaking of themes, if you’re one of those mad people who edit them right in the browser, you’ll like the code syntax added to these things. There is also new screen options on a per page basis, and a ton of bugs are ironed out.
As for compatibility, most plugins and themes will work. There’s nothing groundbreaking in the core code department, so you can probably update right away. Get it now, and see the updated Codex page for a more in-depth look on the changes.
Below is the demonstration video from the devblog post: