The latest version of the plugin brings a new ‘dropdowns’ mode to the Taxonomy Drill Down widget. I’ve also added a few filters so you can further customize the appearance, without modifying plugin files. They can be found in query-multiple-taxonomies/widget.php.

new widget interface

Also, a single widget handles multiple taxonomies now. Hovering over a taxonomy will show you the post types it’s associated with.

If you’re currently using an older version, you will have to re-add the widget after upgrading.

On the template side of things, all taxonomy archives (multiple or not), now go to taxonomy.php, instead of multitax.php. Also, is_multitax() now accepts an array of taxonomy names to check against:

if ( is_multitax( array( 'colour', 'shape' ) ) ) {
  // Both the colour and shape taxonomies were queried

Last but not least, the plugin has been better integrated with the WP_Query class, fixing a number of bugs in the process. For example, besides query_posts(), you can also use new WP_Query(...) now.