Ender Labs has Zephyr for App.net (iTunes Link) for the iPhone, iPod Touch, and iPad in the iTunes App Store for FREE (regularly $4.99) for a limited time.

Fast. Powerful. Clean. Zephyr is an App.net client for iOS. This universal app can be enjoyed on all of your devices – iPhone, iPod touch, and iPad.

Post, star, and reply to threads through an intuitive interface and enjoy App.net with lightning speed.