We launched our JDBC code generator for Oracle SQL Developer 1.5 in July 2008. It's been a great success - as of today we've had 15,699 downloads from 10,363 different IP addresses. To add it to your copy of SQL Developer start the "Check For Updates" wizard and then choose "Third Party SQL Developer Extensions".
Once installed you'll find that an "OrindaBuild" files folder is added to the folders that appear under each connection. When you double click on the file you open OrindaBuild for the parent connection and can create Java to run your PL/SQL procedures, access tables or call any SQL statement. For more information see here.
The demo version of the product expires after 6 weeks, but we allow repeated demo installs provided you don't use the product commercially.
Currently the product doesn't handle write Java to call PL/SQL procedures that take ARRAY or VARRAY objects defined inside PL/SQL packages. We have just finished implementing this and will release a Beta within a week or so. This means that OrindaBuild will soon be able to write Java to call pretty much any PL/SQL that lives inside your Oracle database, even if it can't be directly represented using JDBC.
Note: On May 17th 2010 OrindaBuild was renamed to JDBCWizard