Google Phone: Another walled garden?

Link: Google enlists help for Google Phone – USATODAY.com.

"The Google Phone, powered by the new G-system, could blow open this model by providing easy access to the Internet at PC-type speeds. One caveat: You’ll have to use Google for navigation. Still, Gillis says the Google Phone could push cellphone carriers to improve their game considerably. ‘This is likely to accelerate the demise of the walled garden, and consumers everywhere will be the big winners.’"

In what way is a phone operating system which makes you use Google for navigation not a form of walled garden? You’re still just free to roam only where the provider – in this case Google – lets you.