A Quantcast mobile trends report says that mobile web activity grew 110% in the US throughout 2009, and of course Apple was responsible for most of that, with a 65% market share, 41% from the iPhone and the rest from the iPod touch. Apple's market share slightly dropped in 2009 (due to increasing competition), but it's still head and shoulders above everyone else.
App downloads are huge as well. Not only did Apple announce that three billion downloads, but Gameloft says they've reached 10 million paid downloads of apps by themselves, and developer Lima Sky (makers of Doodle Jump, one of our favorite games of 2009), says downloads skyrocketed after Christmas, with over 500,000 downloads of their app in December of 2009 alone.
The App Store is doing big business lately -- it's probably a safe bet to say that 2009 kicked off a golden age of mobile web activity. And all indications are that 2010 will be even more interesting.