I've burned 25 DVD Audios in the last couple of days, using DiscWelder Bronze.
The program is 89 dollars, and Frank, at Cascade Media sells it.
It's also gapless. Which DVD Architect isn't.
The user interface isn't the greatest, but the end product is really nice.
You can't drag and drop tracks... arghh.. You have to double click each and everyone..and you can't save image files, unless you pony up and by the expensive version...
Wavelab 5, which was just released, also burns DVD-Audio; however, I've yet to see it.
These are your options, for now. Unless you have 50K plus, and want to spring for Sonics commercial applications.
Peace,
Dave