• by Mark Walsh  @markfwal, December 18, 2009

No wonder marketers get more excited about advertising on smartphones than feature phones when it comes to mobile devices. According to the latest monthly data from AdMob, smartphones accounted for nearly half (48%) of mobile Web and application traffic on the mobile ad network in November, up from 30% a year ago.

Since only about a quarter of U.S. mobile customers own smartphones, they're clearly overrepresented in mobile Web browsing and app use. Meanwhile, the share of traffic generated by regular phones has fallen over the last year from 70% to 52%.

Much of the smartphone growth results from the continued popularity of the iPhone and the proliferation of Android phones. The latter accounted for 27% of U.S. smartphone impressions in November, coming from devices including the Droid, HTC Magic and HTC Hero.

Research released by comScore Thursday also showed 17% of smartphone buyers plan to buy an Android phone in the next three months, up from 7% in August (when there were only two available, the T-Mobile G1 and the T-Mobile myTouch). There are now 14, with a bunch more expected next year, including Google's own Nexus One device.

The Web tracking firm also found that Apple and Android device users were more likely to interact with mobile media than an average smartphone users, at 94% and 92%, respectively, versus 80%. (Only 26% of non-smartphones subscribers were using mobile media.) The finding highlights that Android is also quickly becoming the second most important mobile platform for advertisers and developers after the iPhone/iPod touch.

Monthly metrics released by AdMob rival Millennial Media Friday showed Apple is far from fading, though. Impassions generated by the iPhone/iPod touch increased 42% in November--the biggest monthly jump to date--and Apple increased its share of U.S. impressions among phone makers to 26%, regaining the top spot from Samsung. (Millennial estimates smartphones drive about 40% of impressions.)

And worldwide, Android still has a ways to go to catch up with the iPhone. The voluminous Mobile Internet Report released by Morgan Stanley this week estimated the Apple device globally accounts for 65% of Web browsing and half of app usage, compared to just 8% and 11%, respectively, for Android. But all indications point to the gap closing in the coming months and years. Either way, the two titans battling it out to broaden mobile media use is good news for advertisers.