Any ideas on 'when' 64 bit will be commercially ready.
It is commercially ready given that you have the right components. The biggest problem right now is sound card drivers but they are coming out one after one now. There are other things like FXTeleport, MoL and things like that that can stop the show, but I THINK it's fully possible to use XP64 on slaves right now. Hosts are a problem right now, but the intermediary step with 32-bit apps and a 4GB limit should work fine. This is not anything I've tested so don't quote me on it... I actually planned to try it and I have XP64 and 64 bit hardware, but I don't have any sound cards with 64-bit drivers...
As far as 64-bit hosts go you're restricted to...Sonar right now I think. Sonar 5 which was released last fall includes both 32-bit and native 64-bit builds.
That said...you'll be living on the edge of technology if you go there now which is good and bad... I think the big 64-bit revolution will come when Vista is released.
/Mattias