There has been  an almost  complete new set of browsers released  in the last two months from all the major browser vendors. So these new browsers are included in these tests using the revised 450 item benchmark. The browsers are ranked by their % compliance  scores with Google Chrome the best and IE 9 and 10 the worst.

Browser HTML5 Compliance Rankings
Browser HTML5 Test Results
Chrome  14.0885 341/450=75.8% +13 bonus points
Firefox 7.01 313/450=69.6% + 9 bonus points
Safari 5.1 293/450=65.1% + 9 bonus points
Opera 11.50 286/450=63.6% + 7 bonus points
IE10 2nd preview 231/450= 51.3% + 6 bonus points
IE9.0.8182 141/450=31.3% + 5 bonus points

The real problem here is that there are  some contentious HTML5 standards such as touch and gestures, Web Offline, Metadata, Web Database have to be agreed to. And the various vendors are starting to set out seriously different positions. Given that HTML5 and Adobe AIR are the last two cross platform development tools that can claim any degree of portability among desktop+mobile OS[yes AIR runs on iOS], HTML5 compliance now becomes a critical issue not just for developers and users but IT shops and CIOs.