PAX ’08: Live Anywhere Still Coming, iPhones Too
The reason for the delay is because Microsoft are currently working on other high priority things. These include the new Xbox Experience, Avatars, etc.
They’ve also stated that LIVE Anywhere will also come to iPhones, saying that: “Sure, why not. Plenty of Xbox 360 gamers have iPhones”.
[Microsoft Hasn’t Forgotten About Live Anywhere, iPhone Either]