This article covers  a great deal of information for the guys who want to leverage html5 features but are reluctant to try as IE 6 - 8 comes into picture. I am just wondering if there is polufill available for each and every html5/css3 feature. say I want to leverage css3 properties like box shadow, text shadow or say html5 video, audio tags. Is there certainly a polyfill available for all of those.