Google now has two apps that have amassed more than 1 billion installations each. Gmail was the first, and now there's Google Maps. To be clear, though, that's a little different than 1 billion downloads of, say, the Android Central App, which doesn't come preinstalled on any phone that has access to Google services. As we wrote when Gmail hit the Big B, "there are downloads, and then there are downloads." (If Google wants to bundle us, though, we'll be more than happy to oblige.) If anything, it's a better indicator of just how many Android devices — and proper, Googly Android devices — are out there.
That should in no way diminish the magnitude of the number, however. A billion installations of anything is a big deal, and mad props to the Google Maps team for what arguably is the most important mobile app out there.
For more on downloads, installations and statistics, see this post.