Not using a hack involving the dynamic template generation (in your wp-content folder) .. this makes use of the new wp_is_mobile() function:
use this as extra MD5 salt hash:
(wp_is_mobile()) ? 'mobile' : 'desktop')
This will serve a mobile version of your template (if you have any) and a desktop version to desktop users.
Handy If you have a plugin like WPtouch 🙂