I really thought nobody was using Native Client. It will boost very much their Chrome OS.
Anyway, being sandboxed, despite its benefits regarding security, I find it pretty limiting for real world apps, except games. If it can't even access the filesystem it is pointless to port any non-game app to Native Client for Chrome
I don't understand why people would develop for Native Client instead of just using Flash. Wouldn't you want to allow anyone to run the program, rather than restricting it to just Chrome?