Google has been talking about Native Client for quite a while now. It promises to bring the full power of native apps to the web. But Google's the only major browser maker behind the project, web technologies that aren't adopted by more players rarely catch on.
But now that Google has made it possible for developers add Native Client apps to the Chrome Web Store and now that the first Native Client apps have debuted, it may not really matter that it's only Google behind it.
Because what is there, already, is hugely impressive. You only need to install
Bastion, a very fun and somewhat popular game released for the Xbox and the PC earlier this year, from the Web Store and see it running in a Chrome tab, perfectly smooth on Linux, Mac or Windows to understand why Native Client has a really good chance of getting adopted by everyone.