On June 1st, we'll be retiring ReBirth for iPhone from the App store, to better focus our mobile music making offering.
If you want ReBirth for iPhone for your collection of Propellerhead apps, you have until June 1st to purchase it. After that, you'll be able to use it as it is, but we won't be supporting it and you won't be able to upload your songs. You also won't be able to download it again if you delete it from your device and your iTunes apps folder.
If you have an iPad, there's of course ReBirth for iPad to fulfill your squelching needs: http://itunes.com/apps/rebirthforipad
/Kalle, Product Manager Apps