Google (at the moment, at least) is probably the only outfit on the planet with the cachet to pull it off.
Or Apple. I was thinking about this the other day. Apple does make a lot of money on the Mac hardware they sell, but they also now have a growing non Mac market with the iPod, and iPhone. Plus they also have 18 billion in the bank. So, they now have a good setup to at least experiment with the idea of releasing their OS to a wider market. It doesn't have to be built to work on every system out there nor sold in retail. Instead, they can release a hardware spec list, similar to what Microsoft does, and license the OS to a few other OEMs like HP or Dell. Think of it like the HP branded iPod deal, but letting the other OEM do more of the hardware part.