I am not sure what and when will be feasible in the 90nm node. But I see what is feasible "in a nanosecond" if AMD would choose to offer it: Dual chip module Opterons.
Although I dont expect such an offer in the near future. It would just be a nice option to consider in case Itanic would surpringly gain some traction.
What I could imagine though is to see DCMs in Red Storm in Summer as a HPC-edition, just for the mindshare it would deliver.
And an appropriate offering for Striders. With a four-digit pricetag.