Night Optics USA, a Bushnell company, is now selling night vision adaptor kits for the iPhone 4/4s/5. The new kits allow a user to use the video recording capabilities of the iPhone through a variety of night vision weapon sights and vision systems.
MSRP on the kits range from $184.99 to $189.99, not including the actual night vision optics.
Adapting the iPhone to gun optics is not unique to Night Optics USA. Steve has previously reported on similar devices here and here.