Well thats the thing though int it,
you need to have other things working at that speed to be able to use it, also you would need the demand for it. Just cos it can go that quick dont mean it will be going that quick.
Though it will still make a difference with that kinda seek time and transfer rate.
Load times for everything will improve also boot times.
At the moment WD Raptors are the only HD's using 10,000 RPM that I know off and seek times are pretty much half the time of everything else.
There is an 74 Gig WD Raptor thats been out for a while now but it does not have some of the new features that are used in this new 150Gb one.
http://www.novatech.co.uk/novatech/specpage.html?WD-740GD