Downloads from Apple’s App Store have surpassed a whopping 15 billion since the store launched in 2008, the company announced today. That’s another strong milestone for the iOS App Store, which houses applications for the iPhone, iPod Touch and iPad.

The announcement proves that iOS app downloads are indeed accelerating. Apple just announced in January that it had surpassed 10 billion app downloads.

Apple said it has 425,000 free and paid apps in the App Store, which refutes a third-party estimate from May that suggested there were over 500,000 iOS apps available. The App Store houses over 100,000 native iPad apps (meaning they’re optimized for its bigger screen). Apple noted that it has paid out over $2.5 billion to app developers so far and that there are over 200 million iOS device users around the world.

The 15 billion download figure is a reminder of just how much Apple is ahead of the competition. Apple, after all, pioneered the concept of the App Store by making it a key feature of the iPhone in 2008, and its clear-cut revenue sharing tempted developers to make apps for the iOS platform (Apple gets 30 percent of app purchases, developers get 70 percent).

In comparison, there have been over 5 billion Android apps downloaded so far, according to AndroLib, a site that makes it easy to find and download Android apps.

We’ll be exploring the most disruptive mobile trends at our fourth annual MobileBeat 2011 conference, on July 12-13 at the Palace Hotel in San Francisco. It will focus on the rise of 4G and how it delivers the promise of true mobile computing. We’re also accepting entries for our mobile startup competition at the show. MobileBeat is co-located with our GamesBeat 2011 conference this year. To register, click on this link. Sponsors include Verizon Wireless, Qualcomm, Flurry, Greystripe, Box, Moolah Media, Tapjoy, AT&T Interactive, YuMe, Zong, Kontagent, Papaya Mobile, Acaltel-Lucent, Spil Games, BluePoint Security, PayPal, Xyologic, VSC, and Vantage Communications.