[css3-images] asymmetric radial gradients

I was looking through Brad's comments on the radial gradient syntax, and one of the
things that stood out was the broken expectation that moving the center would shift
the center of the gradient while keeping the outer rim the same -- an effect that
would create an asymmetric radial gradient, like this:
   http://www.amanith.org/images/Radgrad.png

I'm not saying we should add this capability right now, but I'm a little concerned
that we might be locking ourselves in here. If we were to add asymmetric radial
gradients in the future, how would that look? How would it interact with the
symmetric radial gradient syntax we have now?

~fantasai