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You use a combination of multisite and Wurfl.. WURFL will contain the settings for your phone, but you will need to make a theme for mobile.yoursite.com and set the theme with multisite, then also making a redirection to that subdomain if a WURFL Device is detected.
This is one way..
Generally a mobile theme is 1 column, with the left and right blocks sections either the left at the top of the center with the right at the bottom or both left and right at the bottom of the center block.