dacaw - I wasn't there, but AMD's engineers are there ;) And they know, what they are doing and seeing.
The original Opteron took a long time from first tape out to a final product (let's count stepping B3 from april '03 as final).
90nm Opteron wafers have been produced already more than 12 months ago. That'll end up as a bit more than 12 months before you can buy the first 90nm Opterons. Validation of 90nm dual core K8 might take about the same time as the 130nm->90nm shrink. So also from this point it's about the time where AMD should be testing first dice to have them ready in 2H05.