MediaChance has just released a free beta of a new DVD authoring tool called
DVD-LabPro. From the looks of it you can do pretty much anything allowed in the DVD spec with it--8 audio programs, subtitles, and so forth.
The official release is supposed to be in the next month or two, and the retail price is $199.
I've made a few comments about DVD-Lab in the past. I use a powerful authoring program called Maestro, and DVD-Lab looks suspiciously similar in many ways. Hmmm...