Google has launched a backup tool inside the already-approved Google Drive.
According to Google’s switching guide, install the Drive app on your iPhone and run the backup wizard by heading to Menu > Settings > Backup.
Here, you can back up your contacts, calendar events, photos, and more. When you set up your Android phone, you can import all of that data. It’s a bit of a workaround, since Apple won’t allow a dedicated app to help switch to Android, but it should work just fine.