Oracle has put the Application Express Listener up for download. It’s an early adopters release, so it’s not supported, but I think it’s still worth giving a try.
The download is available at: http://www.oracle.com/technology/products/database/application_express/html/apex_listener_download.html
I think it’s a very significant change in Apex. This allows developers to use their existing web server (like Tomcat or Weblogic), instead of Oracle HTTP Server/mod_plsql or the XDB HTTP protocol server/embedded PL/SQL gateway.
Read the Installation Guide for more information.