The iTunes App Store is a force that seemingly can’t be stopped. Today Apple announced that the app store had surpassed over 1.5 Billion downloads and now contains more than 65,000 apps from over 100,000 developers.

Impressively, downloads from the iTunes App Store aren’t just growing, they’re accelerating. It took Apple about 6 months to reach 500 Million downloaded apps while the next 500 Million downloads took only 3 months. Since then, the app store has amassed 500 Million more downloads in less than 3 months.

By way of comparison, it took nearly 3 years before the Billionth song was downloaded from iTunes. The iTunes App Store hit the Billion milestone after just 9 months. Granted, many of the app store downloads are free, but the sheer volume is still impressive.

In the press release issued today, Steve Jobs noted,