Absolutely great news! This is the kind of progress we should be seeing in web technologies.
Transitions are specified using the following properties:
transition–property – What property should animate, e.g., opacity.
transition–duration – How long the transition should last.
transition–timing–function – The timing function for the transition (e.g., linear vs. ease–in vs. a custom cubic bezier function).
transition – A shorthand for all three properties.
Download the latest nightly build and see the animations in action for yourself.