The image, screenshot above, shows an iPad mini. The word "Thanks" is shown written in FiftyThree's popular Paper app.
At the time of this writing, it's unclear if the 50 billionth app downloaded was Paper. It's also unclear exactly who downloaded that app, but that person will win a $10,000 iTunes gift card. In addition, Apple will award a $500 App Store gift card to the runners up: The following 50 customers after the milestone download.
Ironically, the 50 billion app milestone was met on the same day that Google announced -- at Google I/O 2013 -- that its own app store, the Google Play Store, had served up over 48 billion downloads.
While the iOS App Store is still ahead of Android's marketplace, it isn't expected to continue in that position. Almost all believe it is only a matter of time before the Play Store passes the App Store in terms of download, despite launching several months after Apple's market.
The iOS App Store was launched on July 10, 2008. The Google Play store, nee the Android Market, was launched on October 23, 2008.