Just reporting that the latest dev channel version of Google Chrome runs NaCl demos (using local Python-based server) and WebGL demos beautifully on the 64-bit Ubuntu 10.04 computer I'm using. Just '--enable-nacl --enable-webgl' (and maybe '--user-data-dir=...'), and you're running.
Don't use this configuration for everyday browsing, of course. Who knows how many security holes there are.
Chrome Extensions are a piece of cake to work with, too. I hope Mozilla Jetpack gets Firefox there soon. Old-timey Firefox extensions are just painful. Well, not that I should need an extension if I have NaCl, but it's still nice. And the extension would potentially allow one load for all sites instead of separate load per site.
Hrmm. Next question, can I put Bullet Physics into Chrome NaCl without much blood, sweat, or tears? If so, I think I won the sweepstakes.
Please say we get this stuff by default in our browsers soon. Pretty please. I mean, I can't hardly believe how nice this would be.