We tested out a few of the most popular browsers to see how ready they are for HTML5 and this is what we found out. For this test we used http://www.html5test.com which offers an HTML5 testing page and a rating system that goes up to 400 points depending on how many HTML5 features are already implemented into the browser.
Internet Explorer 8 is pretty far behind the curve. IE scored a total of 32 points out of 400. Pretty dismal showing for what used to be the top internet browser in the world. Internet Explorer has been playing catch up with rendering design since the implementation of CSS and their poor showing here tells us it does not seem like much will change in the future.
Firefox 4.0 is next in line and they scored pretty decently getting 249 out 400 possible points. They are still missing a lot of key elements but got bonus points for the audio and video implementation as well as their parsing rules.
So those are the statistics. At the moment the only HTML5 browser that is going to get you very far is Google Chrome and until browsers catch up with the newer language it is probably a good idea to use it sparingly in your designs until it actually is a true and tested standard.