The latest data from AdMob, the world's largest mobile advertising marketplace, shows that Apple now dominates the mobile web in the U.S. with a 48% market share. This growth, interestingly enough, does not just come from the iPhone, but the iPod touch also saw a meteoric rise in usage during the last month. Traffic from the iPod touch to AdMob's network in the U.S. increased 3.4 times from November to December.