Apple has just passed the 100,000 mark for apps available that are tailored specifically for the iPad, according to the App Store itself. That’s up from 50,000 at the end of 2010, and 2,000 at the iPad’s launch. By contrast, Google’s Honeycomb Android operating system launched with just 16 optimized apps according to Kevin Tofel, and now has only around 170 according to recent counts, after four months on the market.

To say that this is bad news for Google’s tablet hopes would be an understatement. Apps are increasingly the method of choice for consuming content on mobile devices, and the sale of apps is on pace to become a $38 billion industry by 2015, according to Forrester Research. It’s becoming apparent that app libraries drive tablet sales, not the other way around.

The iPad is winning in this respect by such a wide margin that it’s hard to call it a competition. Even by its own standards, the iPad App Store is doing well. The iPhone App Store took 17 months to reach the 100,000 app milestone. The iPad version achieved it in less time, passing the mark after 15 months. The Android Marketplace was already doing pretty well by the time the iPhone App Store hit 100,000 titles, with 20,000 apps available just a month later in December of 2009.

If the disparity in app libraries is anything to go by, the tablet battle between Android and iOS won’t mirror the one between the two platforms on the smartphone front. As some have suggested, it’s likely that Apple’s dominance in the tablet market will have more in common with the iPod’s performance among portable media players, which is very good for the future of iOS in general.