Several companies who manufacture digital cameras have issued "silent recalls" due to a faulty chip distorts photos when it fails. Sony, Canon, Nikon, Olympus, and others are affected. Digital Photography Review has more; here's the Nikon D2H & D70 advisory. (A "silent recall" isn't an official recall...the companies are only repairing items in which the faulty chips fail.)
Update: Eliot sez: That's the wrong service advisory for Nikon...it's an unrelated problem. Here's the related advisory...doesn't affect any of their dSLRs.