WordPress 2.3 Beta 1 is now available for download and testing. Some of the features of 2.3 include automatic notification for plugin and core code version updates, built-in tags support, faster javascript, and SEO-friendly URL redirection.
There have been reports of compatibility issues with a few plugins due to the changes to the category system (plugins that only used the API functions should be okay, but those that used direct SQL queries may break). Also, some file moves in the admin area have affected a few other plugins. Please report problems on Trac, and document compatible plugins on the Codex.
I've already installed the beta on one of my blogs and quite like some of the new features, such as tags and automatic notifications. In fact I already found the plugin notification useful, and upgraded one. I have also however seen some bugs. I'm looking forward to the final release.
