Android got some good news this week. Firstly, numbers released by comScore suggest the platform grew in the fourth quarter of 2011 in the U.S. Secondly, the U.S. government has decided to use Android devices as secure phones.

In a story from Fierce Mobile Content, comScore released its 2011 smartphone numbers, finding that of all the mobile platforms available in the U.S., only Android and Apple’s iOS platform saw growth. Android now accounts for 47.3 percent of all smartphones in the U.S., while iPhones take 29.6 percent. Android saw 2.5 percentage points of growth from September to December 2011, and Apple saw a 2.2-percentage point hike during the same period. Overall, comScore says smartphones now account for 40 percent of all mobile phones in the U.S.

Meanwhile, Android just landed another big segment of the smartphone market: government phones. As GigaOM reports, the U.S. government has decided to go with Android for its secure devices over Apple’s iPhone.

It’s specifically because of Android’s “open” structure that the government has decided to use Android phones over other options. The government said that because it can access Android’s code to make changes to it, the way carriers and device makers do as they customize the operating system for their devices, Android phones can be altered and made more secure to meet the government’s needs. Such code access was requested from Apple, but it declined to provide it to the government.

Access to Android’s code allows the U.S. government to very quickly make alterations and issue updates to those secure devices, as well. GigaOM reports that one contractor on the project, Angelos Stavrou of George Mason University, said the government will be able to update its smartphones as quickly as within about two weeks. Smartphone carriers often take months to push through updates for Android’s operating system on their devices, but it seems for the U.S. government, the task is significantly easier.

In all, Android continues to see success, and having its operating system endorsed by the U.S. government for its security certainly doesn’t hurt. It still faces fierce competition from Apple, especially with the iOS maker coming off a big win with the iPhone 4S in the fourth quarter of 2011. In 2012, Google is likely to further push the rollout of the latest version of Android, Ice Cream Sandwich, but it’ll need to stay on its toes to continue the operating system’s growth and success.