Any ideas what DVD authoring software for PCs currently supports the approved HD DVD specification? I think I've heard Sonic mentioned; anything else?

I think we're still atleast a year away from HD DVDs, especially at reasonable prices. I have read that you can make a WMV-HD dvd, but that requires a compatible DVD player.

Be patient and let BluRay and HDDVD finish bickering...

Uhh, HD DVD ships march 28th

you can preorder the players at crutchfield for 499$ fot the toshiba HD-A1


Im also looking for a PC based HD DVD authoring program. Apple's DVD studio pro 4 can do it right now.

Really? I'll look into that. That's cool if it actually does, but I'd still wait.

Sonic is definitely working on a HD capable system. Their site seems to mention HD-DVD:

http://www.sonic.com/products/Professional/HDAuthoring.aspx

I'm pretty sure I saw a seperate package for Blu-Ray last year at IBC as well.
Think they have two different programs for the standards.

Other big players (Apple?) will probably follow pretty soon with software as
well. I expect other to lag behind that for at least a year.

I'm not sure if PC burners have been announced that can be used to burn
movie compliant discs (!). All in all I expect this will be an expensive market
to start in with high costs for the burner, high costs for the software and
high costs for the media.