Probably never. NaCl lets you embed programs into a webpage, protected by a layer in between the OS and the actual code so that it can't break out and wreak hav

Probably never. NaCl lets you embed programs into a webpage, protected by a layer in between the OS and the actual code so that it can't break out and wreak havoc like ActiveX once did. So this means that any website could embed Ruby code (more strictly speaking, it could embed a Ruby interpreter) to be executed client-side on a browser supporting NaCl.