The new white paper can be found under Technical Information on the APEX OTN Page.
Download it from here.
Amitabh Chhibber from the APEX team and Duane Smith from the RAC Pack team worked across different timezones and overcame many obstacles (mainly with available hardware) to produce this excellent white paper on configuring APEX in an Oracle RAC environment.
A special thank-you to Anton Nielsen from C2 Consulting who has done a lot of these installations and was kind enough to review this paper and add some invaluable content.
Barb Lundhild Product Manager - Real Application Clusters was also kind enough to review this paper.
We also have many other white papers covering a variety of different topics in the pipeline.
The first of these the NTLM Authentication is now also available here.
Hope these papers help,