I've been thinking about mobile commerce recently, in part because I am on a panel at the Canadian IT Law Association annual conference tomorrow entitled "Mobile Business: Industry Trends, Public Policy Issues and Legal Implications" along with Jacob Glick of Google, and Eric Gross of Gowlings.
m-commerce is already here, and will grow significantly in the near future. Consider that mobile devices are outselling PC’s.
North America is not on the leading edge of this. Places like Japan and Korea, and parts of Europe are ahead of us.
As examples of what can be done, take a look at these McDonald's interactive billboards. You play a game on the billboard using your phone to win a virtual coupon. (Ironically, the videos in the article at this link might not play on your iPhone).
Also see the virtual grocery store in a south Korean subway station. The walls have images of store shelves. You take pictures QR codes beside items you want, and the store delivers the purchases to you shortly after you get home.