Passport Changes

On June 1, 2009, new passport requirements go into effect for border crossings within the Western Hemisphere. Click on the title of this post to go to the website that lists all the important changes. For scuba divers, this is important as U.S. citizens will now need to present a passport or a passport card when entering the U.S. from the Caribbean, Bermuda, Mexico, and Canada. This is part of the Western Hemisphere Travel Initiative.

Has anyone traveled with the U.S. Passport Card (as opposed to a passport)? Just wondering if there's any benefit to it.

Thanks!
Jenny