25 billion apps have been downloaded from the Google Play store

"Just six months after its launch, Google Play has reached 25 billion-with-a-B downloads.
Play has become the de facto application store for the Android platform, replacing Google’s range of Android app-, game-, and music-purchasing software. Today, the marketplace contains 675,000 total applications, including games.
Before Play launched, Google Music, Google Books, the Android Market, and a few other separate products made up a diverse (and not in a good way) media store for all Google and Android products and devices. The diversity read like fragmentation to frustrated users with app overload."

Source:  VentureBeat, 26th September 2012