Several stories on this today.
“… Mozilla is building a way for people to run browsers with all the powers of current plug-ins, but without the plug-ins themselves.
“Martin Best, the product manager of games at Mozilla, said he expects game developers to be interested in creating browser-based games because it will cut down on a problem that he called “code fracturing.” Developers “only have to support HTML5, instead of many different kinds of native code,” he explained. …” Reviews – Cnet
An asm.js optimiser can currently be found in the form of OdinMonkey in the nightly builds of Firefox; it is due to become a mainstream Firefox component with release of Firefox 22 in June. …”