SAP Portal 7.3 is out and ready to be played with. A simple how-to guide for creating a custom Layout can be examined in the attached PDF document. The creation and deployment process is quite straight forward. One step that I had an issue with is adding the new layout to the list of Default Templates.
When you complete the step of creating a Delta Link in the Portal Content -> Templates -> WPC Templates -> Layouts directory make sure that you open the properties of a new object and check off a property Is Template. Without completing this step the newly created layout will not be displayed amongst the standard few.