Google announced Monday that more than 10 billion apps have been downloaded from the Android Market — a significant milestone in its mobile platform war with Apple.

“One billion is a pretty big number by any measurement,” said Android developer ecosystem head Eric Chu in a company blog post. “However, when it’s describing the speed at which something is growing, it’s simply amazing.”

Indeed, compared to the first two years of Android’s existence, app downloads have increased dramatically in 2011. Between the platform’s release in 2008 until mid-2009, for example, Android Market initiated 1 billion downloads in just under a year. Fast forward to the period from mid-2009 to July 2011, and the number leaps to 6 billion downloads. What’s more, it took only six months for the market to earn its last 4 billion downloads, bringing us to the 10 billion mark today.

In conjunction with today’s milestone, Android Market is featuring 10-cent downloads on select apps over the next 10 days, a move that will only bolster sales numbers further.

Hitting 10 billion downloads is the natural culmination of significant Android Market development over the past year. Google finally launched a web-accessible version of the Market in February, and after months of Android developers complaining about their apps being buried in Google’s store, Google revamped the entire look and feel of the Market during its I/O conference in May.

Of course, much of this was playing catch up to Apple’s much more mature iTunes ecosystem. Around the same time Android hit 6 billion downloads in July, Apple announced it had more than doubled that number, hitting 15 billion apps downloaded from the App Store. And having launched its iTunes music store years before apps even existed, Apple already had a treasure trove of credit card numbers in its database when its App Store went live.

Google is doing its damndest to catch up. Last month, the company launched Google Music, the company’s first earnest foray into offering MP3 downloads and further filling out the Android Market ecosystem. And with the impending release of Android version 4.0 — a.k.a. Ice Cream Sandwich — on the horizon, it’s likely that Market sales are going nowhere but up.