Spindle speed isn't the end all be all.
The lower data density of the higher speed 10k drives means that their speed declines as you increase the amount of data stored on the disk (not making this up) A 7200rpm disk is obviously slower as far as access time and small file reads, but will actually maintain it's speed better when working with large amounts of data, closer to the full capacity of the drive (you can look this up, really)
And i'll have to find this again, but the fastest drive on the horizon is actually a 7200rpm drive with a huge buffer to decrease bus consumption by transmission delay
disc speed is one factor that definitely does contribute to the speed of a disc, but it's honestly starting to sound like the old clock speed battle between AMD and INTEL, when all of the other factors that contribute to the overall performance of the unit were all but forgotten.
The performance of the drive is not 1-dimensional.
The higher disk speed of the raptors has it's disadvantages as well as it's merits.
And i should add, before i get my head chewed off, that i fully acknowledge that the raptor is the fastest hard drive you can buy right now. I'm just saying that it's entirely possible to make a 7200rpm drive that's just as fast in the future, by improving aspects BESIDES spindle speed, like the aforementioned buffer capacity.