Reportedly, in Chrome OS, if you want to run Pharo you need to start the OS in development mode and install a micro linux kernel. Compiling to NaCl would be interesting because Pharo could run on chrome OS in non development mode and without the linux kernel. But I guess there might be some work on other primitives / plugins.��
I think JB was looking into that with Olivier Auverlot at some point.
Clement