Rovio has just announced that Angry Birds Space has rocketed past 20 million downloads across all platforms in the first week. The ratio between paid and free app downloads is still unknown, but Angry Birds Space remains at the top spot of the highest grossing list on the App Store.
Every version of Angry Birds has been more successful than its predecessor which rarely happens. Part of why it's so successful is because of its wide availability across so many platforms. Angry Birds is available on almost every platform known to man. One thing is for sure, if Rovio creates another series of games, Zynga is in for some trouble.