"Publication as a Working Draft does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress." - http://www.w3.org/TR/css3-animations/

Lots of things get promised in IE that don't wind up being very complete, and it'll be quite some time until the IE7/8/9ers fade away.