For goodness sakes, have you guys ever heard of Google?

A quick check there for the data sheets for the Hitachi 7K60 7200RPM 60GB and the Seagate Momentus 7200.1 7200RPM 100GB shows the following power consumption figures:
Hitachi (read/write/seek): 2.5/2.5/2.6W
Seagate (read/write/seek): 2.2/2.4/1.3W*
*Seagate quote an "active idle" rather than seek power, so it may not be the same as what Hitachi is measuring.
Now as to efficiency (ie. how much power is turned into heat), both are 7200 RPM disks. Most heat is generated by the spindle motors. Power is a function of the cube root of spindle speed. Basically the difference in spindle motors will be negligable as long as Seagate has not totally stuffed its motor design up. Since the overall power requirements are slightly lower in the Seagate I would assume that their motors are slightly more efficient (newer design etc etc).
Of course I too wish Seagate would release these little buggers - I want six of them...