Resetting WordPress 3.0 user passwords can be done directly within MySQL through the following procedure.  This assumes your installation of WordPress stores user passwords in the wp_users table as MD5 hashes and the unique site prefix for all WordPress tables in MySQL is _x.

Connect to the database via your favorite GUI (phpMyAdmin, Navicat) or command line with either the WordPress role account or any other MySQL user account with select and update privileges on the WordPress database:

update wp_x_users set user_pass = MD5('123abc890') where user_login = 'administrator';

This will update the password for user ‘administrator’ to ‘123abc890’.  Once this has completed, either flush the wp_x_users table or exit the tool used to access the database to cause the updates to be committed.  Sign into WordPress with the new password and optionally change the password via the user interface.