code by Scott Rockers
If you are going Mobile in a wider sense u suggest using this http://code.google.com/p/php-mobile-detect/
Also for some business categories (eg: cafe, restaurant, cinema) i think that the content users look for while on mobile is the same that as desktop browsers, most likely people search for specific info while on mobile (address, phone numbers, schedules) and probably all the secondary content just slows down the site and bugs the user.
Obviously this does not apply to all sites, just some specific cases…
But it’s just my opinion.