Howtogeek shows you how to use Chrome as your Metro Browser in Windows 8 Release Preview
Windows 8 allows third-party browser to replace Internet Explorer in the Metro environment — except on Windows RT. You can use Google Chrome in Metro today, and Firefox for Metro is on the way.How to Use Chrome as Your Metro Browser in Windows 8 Release Preview
When Windows 8 is released, changing your Metro browser will be as simple as installing Firefox or Chrome and setting it as the default browser. Getting Firefox for Metro at this point would involve compiling it yourself.