I recently recorded a podcast, along with some of the other authors, about writing Beginning Oracle Application Express 4. Here's some more information about the podcast:
A conversation with Patrick Cimolini, Martin D'Souza, and Doug Gault; Authors of Beginning Application Express 4.
David Peake, Principal Product Manager for APEX, chats with some of the authors of Beginning Application Express 4. They will discuss various aspects about the book including the main reason for the book, who the book is focused towards, and some behind the scene information about writing the book.