The HD DVD vs. Blu-ray war is not over by any means. You have to compare the same title on each format. Earlier this year, blu-ray was outselling HD DVD by 2-1 and it appeared that it was going to be the clear winner. However, since Toshiba lowered the price on their players, Blu-ray is barely outselling HD DVD on the same title. If Fox decided to also start manufacturing HD DVD, I bet it would be enough to tip the scales in HD DVD's favor.
full disclosure: I work in Home Video at a major studio.
-flash