It appears that this firmware update isnit required by every Core 2 Duo iMac and Mac Pro. Users at VersionTracker have reported that the update applies to computers with Seagateis ST3500641AS 500GB (firmware 3.BTD) and ST3750640AS 750GB (3.BTF) hard drives.
These are not the same drive models that Seagate was recently called to task over for a potential fatal design flaw.
Hard Drive Update 1.0 requires Mac OS X 10.4.7 or higher, and is available for download at the Apple Support Web site.