We started to see the Android 4.0.4 Ice Cream Sandwich roll out to LTE Xperia ion (LT28i) handsets last week. The update was made available to Rogers customers (LT28i) in Canada earlier this week with firmware build version 6.1.E.1.19.
However, the Android 4.0.4 ICS update has also started to roll out to AT&T customers in the United States this evening. Owners of the AT&T Xperia ion (LT28at) can upgrade their phone to firmware build version 6.1.C.1.105 and some people are reporting that this is subsequently upgraded to firmware version 6.1.C.1.107 shortly after. You can download the update through PC Companion or Sony Mobile Update Service right now.