For the past few years, Apple's iPhone has benefited from having the best app store of any smartphone platform. Say what you will about Apple's walled garden, it hasn't stopped users from grabbing apps by the billions. Meanwhile, the Android Market started out as a second-class storefront, but steady improvements have addressed developers' complaints and made the market a more hospitable shopping destination. As Android and iPhone head into another year of what should be huge smartphone growth, which platform has the better app store right now? Let's compare the iPhone App Store and the Android Market head-to-head to find out.