For the moment, IOS support is done through panoramas (which work great!). Gigaphotos are not supported yet, possibly due to inherent limitations of the device regarding number and total size of downloaded images, general overall RAM limits, etc.
As a simpler workaround in the meantime we could have the iOS 'site' display a reasonably-sized photo of the gigaphoto, composed of a single image larger than the screen of the iOS device (only two sizes possible anyway). The familiar pinch-zoom gesture could still be used to zoom in an out and even though users don't get the same level of detail at least a seamless experience is delivered that mirrors the one found on Flash-enabled devices. In this manner, even though of less quality, iOS version is not 'crippled'.