Lord help us all if Rails 3 is so different than 2 that they're WAITING to make it compatible with MagLev.

It isn't.. But why do something twice if you don't have to?

What's being done "twice"? The goal isn't to run specific applications or frameworks, it's to run Ruby code.

If they're going to tweak the VM to handle one specific use cases while ignoring others, then it's a not a Ruby VM.