Qimonda may had added their 2 cents to the mix but you never mentioned Samsung and one of the key partners. 

Aside from that memory's one thing but who will be making the mainboards. Rambus makes very fast memory but ways required mainboard users to buy them in pairs, and using terminating C-rimms if you couldn't afford 4 memory sticks of 1gb or $1200 worth of memory. I wonder if XDR will be as expensive as there elders. 

That said I hope we don't get watered down versions like what happened to the Cell processor.