Android Market, the official, Google-sanctioned app marketplace for Android, is announcing a major milestone December 6th 2011: 10 billion total downloads. More important, the rate of growth is surging. Google says that it’s now seeing 1 billion app installs every 30 days.

To give some context to that, it took 20 months for Android to hit its first billion downloads, and another five months to reach its second billion. Asked what’s driving the growth, Google didn’t share any specifics, but pointed to the 550k Android devices being activated each day as the major contributor. The increase in international support and a revamped Android Market have been factors as well.

Android still has a long way to go to catch up to its iOS rival in terms of total downloads — Apple’s App Store has roughly 20 billion cumulative downloads at this point (the most recent stat I can find is 18 billion downloads as of October 4). But the number of new downloads per month is probably more important to developers figuring out which platforms to build for, and the race is much closer there — during the same event, Apple also announced it was seeing one billion monthly downloads.

The story is less clear for developers building premium apps, though. During its October event Apple also announced that it’s paid developers on iOS $3 billion to date. Google isn’t breaking that number out for Android, which likely means it doesn’t have anything to boast about on that front.

To mark the occasion, Google has teamed up with a number of Android developers to offer a special promotion. For each of the next ten days, it’ll be offering a new set of top applications for 10 cents each (the apps are all normally priced between 99 centers and $6.99). Google isn’t eating the cost of the discount, but instead asked the developers if they’d be willing to participate in the sale.

Also worth noting: while Android Market is far and away the most popular way to download Android apps at this point, the open nature of Android means that users can install third-party marketplaces, and device manufacturers can pre-install competitive markets as well. Amazon is the most prominent company to this with its Amazon App Store (which you can download to any Android device, and comes pre-installed on the Kindle Fire). In other words, while the iOS App Store is the only place for users to download apps, Android Market doesn’t account for all app installs across Android devices.

I spoke with Jeremy Statz, the founder of Android developer Kittehface Software, which makes several popular live wallpaper apps including Snowfall. Statz has been developing popular apps for Android Market for years now, so he has an unusually good perspective on the state of the marketplace.

Asked what the biggest inflection points were in Market’s growth, Statz says that the launch of support in South Korea was big, and that the company typically sees a surge in downloads around the holidays (which isn’t surprising — other developers on both Android and iOS often see the same). But aside from that, it doesn’t sound like there were any specific launches or events that resulted in more downloads. Rather, it’s been the steady (and fast) rise in Android’s install base, as well as the gradual improvements in international  support.

I also asked Statz about Android users’ willingness to actually pay for apps. Google didn’t break out any data around the number of paid downloads, and Android has gotten a reputation for having users who will gladly download free apps but aren’t nearly as willing to cough over any actual money, at least not to the extent iOS users are. But Statz says he hasn’t witnessed this trend — even since the early days of Market, he says the number of users converting from the free version of his Live Wallpapers to the 99 cent premium versions has been around 2% (he says 1% is generally considered “good”).

via TechCrunch.