In a conversation with a Google employee who is working on the Glass project, Frederic Lardinois was informed that they are adding more-complete iPhone compatibility to Glass “very soon”:
Glass, the Google employee told me, will soon be able to handle these features independent of the device the user has paired it to (and maybe even independent of the Glass companion app).
While Glass will happily work with any iPhone over Bluetooth or use any Wi-Fi connection to get online, iPhone users are currently unable to get turn-by-turn directions through Glass – one of its killer features. Those direction are pretty useful while you are navigating a new city and they do show off the power of location-based apps on Glass, but the software will currently balk if you ask it to give you directions while it’s connected to an iPhone.
For Android phone users, Glass owners have to run a companion app on their connected phone to enable all of Glass’ functionality. However, it is unclear how complete feature parity is going to be achieved on the more-restricted iOS.