I just created a GMail account. The first step is to enter your name and your cell phone number. GMail then text messages you a numeric code needed to complete the application.

I'm not sure why they do this, other than to be cool, but it was a new experience for me. Perhaps they are showing off their technical prowess, or introducing you to one aspect of their GMail functionality. GMail does provide IP telephony and text messaging via your browser.

As far as user experience goes it was kinda neat, but the impractical nature of having to access your cell phone just to do something that really didn't require a phone isn't big on usability.