The official announcement: http://www.getrailo.org/index.cfm/whats-up/railo-33-released/
What's new (on the wiki): http://wiki.getrailo.org/wiki/What's_New
What got fixed (also on the wiki): http://wiki.getrailo.org/wiki/What's_Fixed
It's worth noting that Railo 3.3 installers have been rebuilt and it now uses Tomcat 7. Thanks to Jordan and the community for providing it!
Onto the next!