Previously limited to only 50MB APK files alone, Google is now allowing app developers to upload up to 4GB in extra resources as app attachments in Android Market. This move will increase the clarity on actual app size and help in curbing out the two-phase download process for large games and apps. The maximum APK file size is still 50MB, but devs will have two expansion files, each one up to 2GB.
Traditionally for large apps or games, Android users had to download the main app/game from Android and then open the app and complete the rest of download. This would often result in the expiry of Market refund time and if you didn’t want that specific game or app, you were struck with it. But now, refund period won’t start until all the app files are downloaded.
On most newer devices, when users download your app from Android Market, the expansion files will be downloaded automatically, while on older devices, your app will download the expansion files the first time it runs, via a downloader library which we’ve provided below.
Developers can learn more about expansion files and other details at the Android Developers Blog.