Found this somewhat interesting and somewhat useful site. You can look up new features of HTML5 and CSS3 and see if they are features that are supported by a number of browsers/devices. Should you be using them now? It tells you if it's okay, good with fallbacks or polyfills or whether you should avoid using such features right now. Just a quick little reference tool. It seems as though it's still pretty new. I'm sure they'll continue adding information.