I know I'm a bit late chiming in here, but I don't know where the reports of low quantities (or no production at all) of the 1333MHz FSB Clovertowns came from. It's bogus. Intel went through their official launch of these new quad-core chips today and all are available - even the 120W 2.66GHz monster.
HP is Intel's official launch partner for the new Core 2 Quad Xeon chips and they have been taking pre-orders from corporate customers for a few weeks now. They are expecting to start shipping 8-core workstations within the next 10 days.
I'm not sure what Apple's timing will be with an 8-core release, but it could be as soon as tomorrow. Realistically, I think it more likely to be next tuesday (as always), but if they delay until after the Thanksgiving holiday that wouldn't surprise me either. I doubt they will wait until MWSF... By then, Dell, HP and others will have sold thousands of 8-core systems.
Now as far as offerings given the official specs of the new quad-core CPUs, I would expect the 2.33GHz Clovertowns to be a drop-in replacement for current Woodcrest models -- as far as the Mac Pro is concerned. If they offer the 2.66GHz chips, it may require an updated logic board and/or VRM pack to handle the power requirements. Most likely a different cooling system will be required too, so who knows what that will do for availability and pricing. It will probably be quite a bit more expensive, but an extra 330MHz per CPU core could be significant as long as the applications involved aren't overloading the FSB or already stressing it at 2.33GHz.
Just wanted to add that the lack of higher speed dual-CPU workstations now with the launch appear to be related to mainboard/logicboard delays and not actual chip supply. Intel said that all models will be available in quantity. I think we're seeing the same industry doom and gloom we saw over C2D Merom offerings where a lot of sites were claiming shortages when there were none. Intel is very forthcoming regarding shortages or inabilities to meet demands and production schedules. If there's going to be a lack of production or shortages here in the coming weeks, Intel will let us know.
