WordPress have announced that they areready to release the second beta of WordPress 3.0.
This release includes: Revised menu user interface and changes to the WordPress exporter and importer to make it more flexible.
This release is available for download, but it is not yet recommended to run a live website.
There is a WordPress Beta Tester plugin by Peter Westwood to make testing easier at: http://westi.wordpress.com/2009/06/22/making-it-easy-to-be-a-wordpress-tester/