As I have made device upgrade lists in the past for Windows Mobile, I’m glad to see others are providing updated centralized information on this.
JR Raphael has posted a great listing here, with an easy to use device dropdown picker: http://blogs.computerworld.com/19341/android_40_upgrade_list
For the US side Samsung has posted a nice overview, here, for their devices that will receive ICS but no firm dates from each US mobile operator.
It would appear that most of the newer devices from last year will probably receive an 4.0 upgrade if I’m reading all the information correctly.. JR Raphael also made a article on the overall Q1 status from many of the OEM manufactures here: http://blogs.computerworld.com/19867/android_40_report_card
For the many markets, I think the co-branding and continued UI tweaks and changes done to the base models just continue to make it more difficult to support long term. We have seen this for years now, and now on various mobile OS platforms.