That's an old recall, for some reason Ford's sending out the notifications on it again. It is a real problem, several vehicles have burned down because of that short, and there was a story years back on a guy that lost his home when the truck went up in flames in his garage.
It's not just for pickups either, my dad got the recall on his '93 Crown Vic, and IIRC it was done on my Mark VIII as well.
If it's still available there was a vin checker at Fords website where you punched in your VIN and it'd tell you if the recall applies to your vehicle and if it had already been repaired or not.