SAS seems to be the future with insane 15k capacity and outstanding read/write. Wish i could afford a pair!
http://www.cluboc.net/reviews/hard_drives/SAS/seagate/cheetah15K.6_450gb/p1.asp
http://www.cluboc.net/reviews/hard_drives/SAS/seagate/cheetah15K.6_450gb/p1.asp