In Vegas 3, will there be any way to slave track envelopes?
That is, create one envelope on a track, and instance that
envelope onto other tracks? That way, you could control
multiple tracks with a single envelope.

I know you can copy and paste envelopes, but that is not
good enough. If you make changes, you have to copy and
paste again. And if you have more than one or two tracks,
it becomes unnecessarily cumbersome.