The first beta version of WordPress 2.0 has been released here for testing.
“It is pre-release software, which means that you will run into bugs while using it. If you’re not comfortable using unfinished software, please wait until the final release before downloading it.”
The feature list for WP1.6 is included and listed here. Dang, and no importers for Expression Engine? Why, oh why?
You can go ahead and download for a test blog but I don’t recommend upgrading your current setup now. Just check out how it goes and what’s in store for your WP when this goes to final release.