Vince -- thanks for the link. Very nice!
Steve -- The GM schematic shows the entire circuit fused with only a single 30 amp fuse. The relay just interrupts power to the circuit until you turn on the ACC switch or have the car running. Plus, it's just the one seat. Other than making the seat un-powered unless you turn the ignition switch, I can't see any usefulness for it, but I thought I'd ask.
I have Caddy Catera bucket seats in my coupe (actually made by Recaro -- 6-way, heated,leather and about $200 each -- very nice), both power. Even though GM used a single 30-amp fuse for both, I wired separate circuits and separate fuses for each seat. The drivers seat has a computer control that requires a gray wire to connect to the door switch and be grounded (door closed) before the seat will move - I just grounded it. GM engineers must be inundated with memos from their legal dept. about litigious customers who ADJUST THE SEAT WITH THE DOOR OPEN AND THE CAR NOT RUNNING!!!! Heaven forbid such things occur!!!