I wonder how the new
Seagate 5mm laptop HDD will fare...good thing the casing is made of steel. (But then again, it doesn't look like very thick steel.)
They've also released SSDs for laptops, and a desktop hybrid drive (with two models - a 2-platter 2TB and 1-platter 1TB; why no 3TB model???).
Also, Hitachi has squeezed three platters into the traditional 9.5mm 2.5" form, resulting in a 1.5TB 5400RPM drive.
LATE EDIT: I just found out that IBM squeezed 4 platters into 12.5mm with the Travelstar 32GH back in 2000.