Word on the street is that Western Digital is working on a 20k rpm addition to its Raptor line of hard drives, apparently as a way to steal some of the thunder from the fast-growing solid-state disk movement.
As usual with these kinds of rumors, details are sketchy, although some are speculating that the device will mimic the new VelociRaptor in that it will be a 2.5-inch drive housed in a 3.5-inch housing. That company is said to be talking about some kind of noise- or vibration-dampening technology to counter the forces generated by a platter spinning at 20,000 rpms.
My guess is that they'd have to do more than that to make the device workable. Heat generation would seem to be a significant problem, as would power consumption. And the final price tag would most likely be on the high side.
But the idea is certainly feasible, provided it could deliver the kind of performance boost to rival the new SSD designs.
Then again, this could just be the last gasp of the magnetic drive community.