Online sources are reporting that Flipboard for Android would be released exclusively on the Galaxy S III. Though it would be for a short time only.
Flipboard already has form on their site where you can enter your email id to get updated on when they release for other devices.
Samsung had a similar deal with Rovio for exclusive Angry Birds levels for their Note smartphone.
This is not a healthy trend for the Android ecosystem but I guess, it would continue as these companies try to differentiate their devices from others!