ApEx 4.0 has been released. You can download the new version of ApEx on the website of Oracle.
You can read about the new features of Application Express 4.0 here.
Please mind that the requirements are changed:
Oracle Application Express 4.0 is supported on all Editions (SE1, SE, EE, and XE) of the Oracle database, 10.2.0.3 or higher. Application Express 4.0 can also be used with Oracle Database 10g Express Edition.