With more than 350 tickets closed, there are plenty of changes. Plugin and theme authors, please test your plugins and themes now, so that if there is a compatibility issue, we can figure it out before the final release. Users are also encouraged to test things out. If you find problems, let your plugin/theme authors know so they can figure out the cause.
More info: http://wordpress.org/news/2011/06/wordpress-3-2-release-candidate/