I already mentioned RiverTrail stuff in another response. I don't really think it is a replacement for SSE/AVX/NEON/AltiVec.

Agreed. So we are getting together with John McCutchan who did Dart SIMD intrinsics to do same for JS via Ecma TC39 Harmony process and rapid prototyping in SpiderMonkey -- and I hope in V8 as well.

/be

+1 to adding the SIMD Dart types into JS. This is how I like to see Google and Mozilla working together to improve the web. (WebRTC is another fabulous cooperation)