Sgolds - Perhaps they expected (and still expect) Itanium to take off?
Does this mean that AMD doesn't build because they don't expect Opteron to take off? Just joking... AMD doesn't build because they don't have the money. Pretty simple.
IMHO, Intel has been planning their 300mm 90nm with the expectation that Itanium would be a growing presence on the desktop by now, and they really haven't brought their factory build plans in line with realistic expectations.
I assume you realize that Itanium isn't on 90nm but imply that Intel expected Itanium to use up much more 130nm capacity, requiring added Fab space for 90nm? I don't think this is the case because the cost advantages of 12" are so compelling that it's unavoidable if you can afford to build it. I also don't believe Intel expected Itanium volume to have a major impact on capacity at the time the 90nm/12" commitments were made. Intel is expecting something else and you may believe their expectations are unrealistic but only time will determine who is right.
If my suspicion is correct then Intel will not open all their new conversions on the expected timetable. They will not man overcapacity to the point where they can not cover the costs of production, and I just don't see what they are going to produce with all that capacity.
May we live in interesting times...