From the original sources,( http://blog.chromium.org/2010/05/sneak-peek-at-native-client... ), it seems that this is only x86/x86-64 compatible, wheras most android deployments run on ARM. I don't know how they hope to get around that, as mobile devices seem to be tied closely to the future to the web.
They're also working on what they consider the Right Thing: instead of sending instructions for a particular processor, send LLVM bytecode and have the client finish the compilation.
I remember reading somewhere from the NativeClient developers that they have thought about ARM, but just didn't focus on it yet. Of course ARM probably requires some significant new code because you can't use the same barrier technology as x86/x86-64 (or so I think).
It's fairly easy to port Android to x86 platforms, in fact we have some working in our lab. The target here would not be mobile devices but set-top-boxes. It's known that Google is working on an Android STB; however, it seems Chrome OS would be another good choice.
