I don't know about you, but I find using a mobile device very inconvenient and time consuming. Personally I would not be surfing the net with my cell phone, that's for sure! And I sure wouldn't be going through any checkout steps.
I'm from the QWERTY keyboard group. I've not yet been able to adjust my fingers to do "hunt and peck" or thumb/index finger routines. It just doesn't work for me. And, I'm so used to blazing along at 80-100 words per minute that a mobile device micro keyboard is out of the question. Too frustrating for me. ;)
But, that's not going to stop me from designing for this user base. ;)