Judging from these leaked pictures, the new Google OS version is hardly revolutionary. Surprisingly, there is a lot of continuity and looks like Android is sticking to its original model. The color scheme has, however, undergone some major changes with Android slowly breaking away from its trademark green and adding a lot of blue to the icons. For people that have been Android fans from the very beginning, this will probably be a huge dissapointment. After all our eyes have grown accustomed to "see green" and it will take a while to readjust.
In general, it appears as if most of the changes are more or less cosmetic so even older phones should in theory be able to to run Ice Cream Sandwich without any problems. With 99% probability, the new Nexus Prime will be the first phone that will come with the new OS version from the box. Some new additions that may become popular: a new multitasking button for quickly switching between your most used apps. Now that's extremely useful!
So when does this baby hit the market before it melts? Unfortunately, it looks like the Ice Cream Sandwich is going to be stored in the Android "freezer" for quite some time.