> our PCI based systems can't handle that transfer rate
> (actually the 64 bit PCI and faster PCI-X slots might
> be able to, but I haven't seen the hardware).

Indeed, I couldn't find any USB3 cards for 64-bit PCI or PCI-X (while there are some for 32-bit PCI).

> Mark's Javascript JIT that he just recommitted to, and
> both ought to be pretty straight forward ports to X64

I doubt a JavaScript-to-PPC JIT compiler can be ported (rather than rewritten from scratch) to any other ISA. Besides, there'd be surely no need for another JavaScript-to-x86(_64) JIT compiler when there are so many already (like for instance the one used in Odyssey on AROS/x86).