Very cool, I've been waiting for this to happen.

I'm surprised that Google doesn't explicitly talk more about this use case for Native Client. It could be the backbone for an AWS/Heroku competitor. The ability to run lightweight tasklets securely would enable a lot of interesting scenarios. While not very significant, Google actually already started doing this with their Exacycle program:

http://research.google.com/university/exacycle_program.html