“In 2013 the next generation of Native Client, called Portable Native Client, will introduce true architecture-independence by using LLVM bitcode as the wire format.”
That’s pretty cool. Portable native code. I imagine they’ll be able to run that bitcode through a verifier/optimizer and cache the resulting native instructions.
An approach like this in general (not just in Chrome web apps) could help with future architecture transitions (like m68k -> ppc -> x86 -> ARM -> ???)
http://blog.chromium.org/2013/01/native-client-support-on-arm.html