Once again, Robert, you've taken me to school. I had no idea!
In fact, now that I've researched it, I've found that you can create a 1280x720 BluRay in DVD Architect Studio.
Just go to the File menu and select Properties. On the Properties panel, set Disc Format to BluRay, then select 1280x720 as the resolution. You can even set the Frame Rate to a variety of progressive rates.
Will these play on any BluRay player, Robert? Or will they play on computers only?