Do they spin down even if the host isn't telling it to do so?
Apparently they did in early firmware versions. I've just checked mine, though, and it's had 270 spin-up cycles in 2500 power-on hours, which sounds about right (two or three a day) for the ones initiated by the OS ("hdparm -S 242 /dev/sda").
Check the head load/unload counts in the output from smartctl -a EDIT: mmm.. that's probably the same as the "Start_Stop_Count", which Andy has already checked. Dunno for sure, though, as I won't allow any of those drives into our gear here.