Google is making news this week unveiling a prototype of its new OS, which is basically a stripped down Linux based wrapper for their Chrome browser. As part of the Q&A, Google stated that other browsers (such as Opera or Firefox) won't run on Chrome OS.
One of the reasons the Google is developing Chrome and the Chrome OS isn't widely discussed, but I think it is fairly obvious.
Google makes it's money from advertising. You can't get an ad blocker for Chrome. And you won't be able to run Firefox on Chrome OS. What Google is doing is ensuring that people will have to see advertising, by luring us in with slick, lean, and fast applications.