In WP 3.3b3 I was using
wp_enqueue_script to load jQuery UI core as well as tabs and dialog, for a plugin I'm developing:
wp_enqueue_script( 'jquery-ui-core' );
wp_enqueue_script( 'jquery-ui-tabs' );
wp_enqueue_script( 'jquery-ui-dialog' );
Without these "enqueue" statements the UI functions did not work. In beta 4 (no changes to my code) jQuery UI elements no longer load, and I can comment out the relevant enqueue statements and the source does not change. Has something else changed in the way WP loads jQuery elements between beta 3 and beta 4 besides the upgrade to 1.7.1?