Back in August, only 7 percent of smartphone shoppers were thinking about going the Android route. The active interest has more than doubled.

Android and Mobile Engagement

So what about actual engagement? AdMob -- the mobile ad-serving company recently -- just released some stats about . The research shows some interesting trends.

According to AdMob, Android phones accounted for 27 percent of all US-based mobile ad impressions last month. That piece of the pie is still significantly smaller than the iPhone's 55 percent, but it's the rate of change that's worth noting.

Within the , Android's share of US mobile ad impressions grew by 35 percent. The iPhone's share, meanwhile, remained static.